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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/4391-0.txt b/4391-0.txt new file mode 100644 index 0000000..0d785eb --- /dev/null +++ b/4391-0.txt @@ -0,0 +1,3245 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 4391 *** + + + + +SELECTIONS FROM THE PRINCIPLES OF PHILOSOPHY +OF +RENE DESCARTES +(1596-1650) + +TRANSLATED BY +JOHN VEITCH, LL. D. +LATE PROFESSOR OF LOGIC AND RHETORIC IN THE UNIVERSITY OF GLASGOW + + + + +From the Publisher's Preface. + +The present volume contains a reprint of the preface and the first +part of the Principles of Philosophy, together with selections from +the second, third and fourth parts of that work, corresponding to +the extracts in the French edition of Gamier, are also given, as +well as an appendix containing part of Descartes' reply to the +Second Objections (viz., his formal demonstrations of the existence +of Deity). The translation is based on the original Latin edition of +the Principles, published in 1644. + +The work had been translated into French during Descartes' lifetime, +and personally revised and corrected by him, the French text is +evidently deserving of the same consideration as the Latin +originals, and consequently, the additions and variations of the +French version have also been given--the additions being put in +square brackets in the text and the variations in the footnotes. + +A copy of the title-page of the original edition, as given in Dr. C. +Guttler's work (Munich: C. H. Beck. 1901), are also reproduced in +the present volume. + + + + +SELECTIONS FROM THE PRINCIPLES OF PHILOSOPHY +OF DESCARTES + +TRANSLATED FROM THE LATIN AND COLLATED WITH THE FRENCH + + + + +LETTER OF THE AUTHOR + +TO THE FRENCH TRANSLATOR OF THE PRINCIPLES OF PHILOSOPHY SERVING FOR +A PREFACE. + +Sir,--The version of my principles which you have been at pains to +make, is so elegant and finished as to lead me to expect that the +work will be more generally read in French than in Latin, and better +understood. The only apprehension I entertain is lest the title +should deter some who have not been brought up to letters, or with +whom philosophy is in bad repute, because the kind they were taught +has proved unsatisfactory; and this makes me think that it will be +useful to add a preface to it for the purpose of showing what the +MATTER of the work is, what END I had in view in writing it, and +what UTILITY may be derived from it. But although it might be my +part to write a preface of this nature, seeing I ought to know those +particulars better than any other person, I cannot nevertheless +prevail upon myself to do anything more than merely to give a +summary of the chief points that fall, as I think, to be discussed +in it: and I leave it to your discretion to present to the public +such part of them as you shall judge proper. + +I should have desired, in the first place, to explain in it what +philosophy is, by commencing with the most common matters, as, for +example, that the word PHILOSOPHY signifies the study of wisdom, and +that by wisdom is to be understood not merely prudence in the +management of affairs, but a perfect knowledge of all that man can +know, as well for the conduct of his life as for the preservation of +his health and the discovery of all the arts, and that knowledge to +subserve these ends must necessarily be deduced from first causes; +so that in order to study the acquisition of it (which is properly +called philosophizing), we must commence with the investigation of +those first causes which are called PRINCIPLES. Now these principles +must possess TWO CONDITIONS: in the first place, they must be so +clear and evident that the human mind, when it attentively considers +them, cannot doubt of their truth; in the second place, the +knowledge of other things must be so dependent on them as that +though the principles themselves may indeed be known apart from what +depends on them, the latter cannot nevertheless be known apart from +the former. It will accordingly be necessary thereafter to endeavour +so to deduce from those principles the knowledge of the things that +depend on them, as that there may be nothing in the whole series of +deductions which is not perfectly manifest. God is in truth the only +being who is absolutely wise, that is, who possesses a perfect +knowledge of all things; but we may say that men are more or less +wise as their knowledge of the most important truths is greater or +less. And I am confident that there is nothing, in what I have now +said, in which all the learned do not concur. + +I should, in the next place, have proposed to consider the utility +of philosophy, and at the same time have shown that, since it +embraces all that the human mind can know, we ought to believe that +it is by it we are distinguished from savages and barbarians, and +that the civilisation and culture of a nation is regulated by the +degree in which true philosophy nourishes in it, and, accordingly, +that to contain true philosophers is the highest privilege a state +can enjoy. Besides this, I should have shown that, as regards +individuals, it is not only useful for each man to have intercourse +with those who apply themselves to this study, but that it is +incomparably better he should himself direct his attention to it; +just as it is doubtless to be preferred that a man should make use +of his own eyes to direct his steps, and enjoy by means of the same +the beauties of colour and light, than that he should blindly follow +the guidance of another; though the latter course is certainly +better than to have the eyes closed with no guide except one's self. +But to live without philosophizing is in truth the same as keeping +the eyes closed without attempting to open them; and the pleasure of +seeing all that sight discloses is not to be compared with the +satisfaction afforded by the discoveries of philosophy. And, +finally, this study is more imperatively requisite for the +regulation of our manners, and for conducting us through life, than +is the use of our eyes for directing our steps. The brutes, which +have only their bodies to conserve, are continually occupied in +seeking sources of nourishment; but men, of whom the chief part is +the mind, ought to make the search after wisdom their principal +care, for wisdom is the true nourishment of the mind; and I feel +assured, moreover, that there are very many who would not fail in +the search, if they would but hope for success in it, and knew the +degree of their capabilities for it. There is no mind, how ignoble +soever it be, which remains so firmly bound up in the objects of the +senses, as not sometime or other to turn itself away from them in +the aspiration after some higher good, although not knowing +frequently wherein that good consists. The greatest favourites of +fortune--those who have health, honours, and riches in abundance-- +are not more exempt from aspirations of this nature than others; +nay, I am persuaded that these are the persons who sigh the most +deeply after another good greater and more perfect still than any +they already possess. But the supreme good, considered by natural +reason without the light of faith, is nothing more than the +knowledge of truth through its first causes, in other words, the +wisdom of which philosophy is the study. And, as all these +particulars are indisputably true, all that is required to gain +assent to their truth is that they be well stated. + +But as one is restrained from assenting to these doctrines by +experience, which shows that they who make pretensions to philosophy +are often less wise and reasonable than others who never applied +themselves to the study, I should have here shortly explained +wherein consists all the science we now possess, and what are the +degrees of wisdom at which we have arrived. The first degree +contains only notions so clear of themselves that they can be +acquired without meditation; the second comprehends all that the +experience of the senses dictates; the third, that which the +conversation of other men teaches us; to which may be added as the +fourth, the reading, not of all books, but especially of such as +have been written by persons capable of conveying proper +instruction, for it is a species of conversation we hold with their +authors. And it seems to me that all the wisdom we in ordinary +possess is acquired only in these four ways; for I do not class +divine revelation among them, because it does not conduct us by +degrees, but elevates us at once to an infallible faith. + +There have been, indeed, in all ages great minds who endeavoured to +find a fifth road to wisdom, incomparably more sure and elevated +than the other four. The path they essayed was the search of first +causes and true principles, from which might be deduced the reasons +of all that can be known by man; and it is to them the appellation +of philosophers has been more especially accorded. I am not aware +that there is any one of them up to the present who has succeeded in +this enterprise. The first and chief whose writings we possess are +Plato and Aristotle, between whom there was no difference, except +that the former, following in the footsteps of his master, Socrates, +ingenuously confessed that he had never yet been able to find +anything certain, and that he was contented to write what seemed to +him probable, imagining, for this end, certain principles by which +he endeavoured to account for the other things. Aristotle, on the +other hand, characterised by less candour, although for twenty years +the disciple of Plato, and with no principles beyond those of his +master, completely reversed his mode of putting them, and proposed +as true and certain what it is probable he himself never esteemed as +such. But these two men had acquired much judgment and wisdom by the +four preceding means, qualities which raised their authority very +high, so much so that those who succeeded them were willing rather +to acquiesce in their opinions, than to seek better for themselves. +The chief question among their disciples, however, was as to whether +we ought to doubt of all things or hold some as certain,--a dispute +which led them on both sides into extravagant errors; for a part of +those who were for doubt, extended it even to the actions of life, +to the neglect of the most ordinary rules required for its conduct; +those, on the other hand, who maintained the doctrine of certainty, +supposing that it must depend upon the senses, trusted entirely to +them. To such an extent was this carried by Epicurus, that it is +said he ventured to affirm, contrary to all the reasonings of the +astronomers, that the sun is no larger than it appears. + +It is a fault we may remark in most disputes, that, as truth is the +mean between the two opinions that are upheld, each disputant +departs from it in proportion to the degree in which he possesses +the spirit of contradiction. But the error of those who leant too +much to the side of doubt, was not followed for any length of time, +and that of the opposite party has been to some extent corrected by +the doctrine that the senses are deceitful in many instances. +Nevertheless, I do not know that this error was wholly removed by +showing that certitude is not in the senses, but in the +understanding alone when it has clear perceptions; and that while we +only possess the knowledge which is acquired in the first four +grades of wisdom, we ought not to doubt of the things that appear to +be true in what regards the conduct of life, nor esteem them as so +certain that we cannot change our opinions regarding them, even +though constrained by the evidence of reason. + +From ignorance of this truth, or, if there was any one to whom it +was known, from neglect of it, the majority of those who in these +later ages aspired to be philosophers, blindly followed Aristotle, +so that they frequently corrupted the sense of his writings, and +attributed to him various opinions which he would not recognise as +his own were he now to return to the world; and those who did not +follow him, among whom are to be found many of the greatest minds, +did yet not escape being imbued with his opinions in their youth, as +these form the staple of instruction in the schools; and thus their +minds were so preoccupied that they could not rise to the knowledge +of true principles. And though I hold all the philosophers in +esteem, and am unwilling to incur odium by my censure, I can adduce +a proof of my assertion, which I do not think any of them will +gainsay, which is, that they all laid down as a principle what they +did not perfectly know. For example, I know none of them who did not +suppose that there was gravity in terrestrial bodies; but although +experience shows us very clearly that bodies we call heavy descend +towards the center of the earth, we do not, therefore, know the +nature of gravity, that is, the cause or principle in virtue of +which bodies descend, and we must derive our knowledge of it from +some other source. The same may be said of a vacuum and atoms, of +heat and cold, of dryness and humidity, and of salt, sulphur, and +mercury, and the other things of this sort which some have adopted +as their principles. But no conclusion deduced from a principle +which is not clear can be evident, even although the deduction be +formally valid; and hence it follows that no reasonings based on +such principles could lead them to the certain knowledge of any one +thing, nor consequently advance them one step in the search after +wisdom. And if they did discover any truth, this was due to one or +other of the four means above mentioned. Notwithstanding this, I am +in no degree desirous to lessen the honour which each of them can +justly claim; I am only constrained to say, for the consolation of +those who have not given their attention to study, that just as in +travelling, when we turn our back upon the place to which we were +going, we recede the farther from it in proportion as we proceed in +the new direction for a greater length of time and with greater +speed, so that, though we may be afterwards brought back to the +right way, we cannot nevertheless arrive at the destined place as +soon as if we had not moved backwards at all; so in philosophy, when +we make use of false principles, we depart the farther from the +knowledge of truth and wisdom exactly in proportion to the care with +which we cultivate them, and apply ourselves to the deduction of +diverse consequences from them, thinking that we are philosophizing +well, while we are only departing the farther from the truth; from +which it must be inferred that they who have learned the least of +all that has been hitherto distinguished by the name of philosophy +are the most fitted for the apprehension of truth. + +After making those matters clear, I should, in the next place, have +desired to set forth the grounds for holding that the true +principles by which we may reach that highest degree of wisdom +wherein consists the sovereign good of human life, are those I have +proposed in this work; and two considerations alone are sufficient +to establish this--the first of which is, that these principles are +very clear, and the second, that we can deduce all other truths from +them; for it is only these two conditions that are required in true +principles. But I easily prove that they are very clear; firstly, by +a reference to the manner in which I found them, namely, by +rejecting all propositions that were in the least doubtful, for it +is certain that such as could not be rejected by this test when they +were attentively considered, are the most evident and clear which +the human mind can know. Thus by considering that he who strives to +doubt of all is unable nevertheless to doubt that he is while he +doubts, and that what reasons thus, in not being able to doubt of +itself and doubting nevertheless of everything else, is not that +which we call our body, but what we name our mind or thought, I have +taken the existence of this thought for the first principle, from +which I very clearly deduced the following truths, namely, that +there is a God who is the author of all that is in the world, and +who, being the source of all truth, cannot have created our +understanding of such a nature as to be deceived in the judgments it +forms of the things of which it possesses a very clear and distinct +perception. Those are all the principles of which I avail myself +touching immaterial or metaphysical objects, from which I most +clearly deduce these other principles of physical or corporeal +things, namely, that there are bodies extended in length, breadth, +and depth, which are of diverse figures and are moved in a variety +of ways. Such are in sum the principles from which I deduce all +other truths. The second circumstance that proves the clearness of +these principles is, that they have been known in all ages, and even +received as true and indubitable by all men, with the exception only +of the existence of God, which has been doubted by some, because +they attributed too much to the perceptions of the senses, and God +can neither be seen nor touched. + +But, though all the truths which I class among my principles were +known at all times, and by all men, nevertheless, there has been no +one up to the present, who, so far as I know, has adopted them as +principles of philosophy: in other words, as such that we can deduce +from them the knowledge of whatever else is in the world. It +accordingly now remains for me to prove that they are such; and it +appears to me that I cannot better establish this than by the test +of experience: in other words, by inviting readers to peruse the +following work. For, though I have not treated in it of all matters- +-that being impossible--I think I have so explained all of which I +had occasion to treat, that they who read it attentively will have +ground for the persuasion that it is unnecessary to seek for any +other principles than those I have given, in order to arrive at the +most exalted knowledge of which the mind of man is capable; +especially if, after the perusal of my writings, they take the +trouble to consider how many diverse questions are therein discussed +and explained, and, referring to the writings of others, they see +how little probability there is in the reasons that are adduced in +explanation of the same questions by principles different from mine. +And that they may the more easily undertake this, I might have said +that those imbued with my doctrines have much less difficulty in +comprehending the writings of others, and estimating their true +value, than those who have not been so imbued; and this is precisely +the opposite of what I before said of such as commenced with the +ancient philosophy, namely, that the more they have studied it the +less fit are they for rightly apprehending the truth. + +I should also have added a word of advice regarding the manner of +reading this work, which is, that I should wish the reader at first +to go over the whole of it, as he would a romance, without greatly +straining his attention, or tarrying at the difficulties he may +perhaps meet with in it, with the view simply of knowing in general +the matters of which I treat; and that afterwards, if they seem to +him to merit a more careful examination, and he feel a desire to +know their causes, he may read it a second time, in order to observe +the connection of my reasonings; but that he must not then give it +up in despair, although he may not everywhere sufficiently discover +the connection of the proof, or understand all the reasonings--it +being only necessary to mark with a pen the places where the +difficulties occur, and continue to read without interruption to the +end; then, if he does not grudge to take up the book a third time, I +am confident he will find in a fresh perusal the solution of most of +the difficulties he will have marked before; and that, if any still +remain, their solution will in the end be found in another reading. + +I have observed, on examining the natural constitutions of different +minds, that there are hardly any so dull or slow of understanding as +to be incapable of apprehending good opinions, or even of acquiring +all the highest sciences, if they be but conducted along the right +road. And this can also be proved by reason; for, as the principles +are clear, and as nothing ought to be deduced from them, unless most +manifest inferences, no one is so devoid of intelligence as to be +unable to comprehend the conclusions that flow from them. But, +besides the entanglement of prejudices, from which no one is +entirely exempt, although it is they who have been the most ardent +students of the false sciences that receive the greatest detriment +from them, it happens very generally that people of ordinary +capacity neglect to study from a conviction that they want ability, +and that others, who are more ardent, press on too rapidly: whence +it comes to pass that they frequently admit principles far from +evident, and draw doubtful inferences from them. For this reason, I +should wish to assure those who are too distrustful of their own +ability that there is nothing in my writings which they may not +entirely understand, if they only take the trouble to examine them; +and I should wish, at the same time, to warn those of an opposite +tendency that even the most superior minds will have need of much +time and attention to remark all I designed to embrace therein. + +After this, that I might lead men to understand the real design I +had in publishing them, I should have wished here to explain the +order which it seems to me one ought to follow with the view of +instructing himself. In the first place, a man who has merely the +vulgar and imperfect knowledge which can be acquired by the four +means above explained, ought, before all else, to endeavour to form +for himself a code of morals, sufficient to regulate the actions of +his life, as well for the reason that this does not admit of delay +as because it ought to be our first care to live well. In the next +place, he ought to study Logic, not that of the schools, for it is +only, properly speaking, a dialectic which teaches the mode of +expounding to others what we already know, or even of speaking much, +without judgment, of what we do not know, by which means it corrupts +rather than increases good sense--but the logic which teaches the +right conduct of the reason with the view of discovering the truths +of which we are ignorant; and, because it greatly depends on usage, +it is desirable he should exercise himself for a length of time in +practising its rules on easy and simple questions, as those of the +mathematics. Then, when he has acquired some skill in discovering +the truth in these questions, he should commence to apply himself in +earnest to true philosophy, of which the first part is Metaphysics, +containing the principles of knowledge, among which is the +explication of the principal attributes of God, of the immateriality +of the soul, and of all the clear and simple notions that are in us; +the second is Physics, in which, after finding the true principles +of material things, we examine, in general, how the whole universe +has been framed; in the next place, we consider, in particular, the +nature of the earth, and of all the bodies that are most generally +found upon it, as air, water, fire, the loadstone and other +minerals. In the next place it is necessary also to examine singly +the nature of plants, of animals, and above all of man, in order +that we may thereafter be able to discover the other sciences that +are useful to us. Thus, all Philosophy is like a tree, of which +Metaphysics is the root, Physics the trunk, and all the other +sciences the branches that grow out of this trunk, which are reduced +to three principal, namely, Medicine, Mechanics, and Ethics. By the +science of Morals, I understand the highest and most perfect which, +presupposing an entire knowledge of the other sciences, is the last +degree of wisdom. + +But as it is not from the roots or the trunks of trees that we +gather the fruit, but only from the extremities of their branches, +so the principal utility of philosophy depends on the separate uses +of its parts, which we can only learn last of all. But, though I am +ignorant of almost all these, the zeal I have always felt in +endeavouring to be of service to the public, was the reason why I +published, some ten or twelve years ago, certain Essays on the +doctrines I thought I had acquired. The first part of these Essays +was a "Discourse on the Method of rightly conducting the Reason, and +seeking Truth in the Sciences," in which I gave a summary of the +principal rules of logic, and also of an imperfect ethic, which a +person may follow provisionally so long as he does not know any +better. The other parts were three treatises: the first of +Dioptrics, the second of Meteors, and the third of Geometry. In the +Dioptrics, I designed to show that we might proceed far enough in +philosophy as to arrive, by its means, at the knowledge of the arts +that are useful to life, because the invention of the telescope, of +which I there gave an explanation, is one of the most difficult that +has ever been made. In the treatise of Meteors, I desired to exhibit +the difference that subsists between the philosophy I cultivate and +that taught in the schools, in which the same matters are usually +discussed. In fine, in the Geometry, I professed to demonstrate that +I had discovered many things that were before unknown, and thus +afford ground for believing that we may still discover many others, +with the view of thus stimulating all to the investigation of truth. +Since that period, anticipating the difficulty which many would +experience in apprehending the foundations of the Metaphysics, I +endeavoured to explain the chief points of them in a book of +Meditations, which is not in itself large, but the size of which has +been increased, and the matter greatly illustrated, by the +Objections which several very learned persons sent to me on occasion +of it, and by the Replies which I made to them. At length, after it +appeared to me that those preceding treatises had sufficiently +prepared the minds of my readers for the Principles of Philosophy, I +also published it; and I have divided this work into four parts, the +first of which contains the principles of human knowledge, and which +may be called the First Philosophy, or Metaphysics. That this part, +accordingly, may be properly understood, it will be necessary to +read beforehand the book of Meditations I wrote on the same subject. +The other three parts contain all that is most general in Physics, +namely, the explication of the first laws or principles of nature, +and the way in which the heavens, the fixed stars, the planets, +comets, and generally the whole universe, were composed; in the next +place, the explication, in particular, of the nature of this earth, +the air, water, fire, the magnet, which are the bodies we most +commonly find everywhere around it, and of all the qualities we +observe in these bodies, as light, heat, gravity, and the like. In +this way, it seems to me, I have commenced the orderly explanation +of the whole of philosophy, without omitting any of the matters that +ought to precede the last which I discussed. But to bring this +undertaking to its conclusion, I ought hereafter to explain, in the +same manner, the nature of the other more particular bodies that are +on the earth, namely, minerals, plants, animals, and especially man; +finally, to treat thereafter with accuracy of Medicine, Ethics, and +Mechanics. I should require to do this in order to give to the world +a complete body of philosophy; and I do not yet feel myself so old,- +-I do not so much distrust my strength, nor do I find myself so far +removed from the knowledge of what remains, as that I should not +dare to undertake to complete this design, provided I were in a +position to make all the experiments which I should require for the +basis and verification of my reasonings. But seeing that would +demand a great expenditure, to which the resources of a private +individual like myself would not be adequate, unless aided by the +public, and as I have no ground to expect this aid, I believe that I +ought for the future to content myself with studying for my own +instruction, and posterity will excuse me if I fail hereafter to +labour for them. + +Meanwhile, that it may be seen wherein I think I have already +promoted the general good, I will here mention the fruits that may +be gathered from my Principles. The first is the satisfaction which +the mind will experience on finding in the work many truths before +unknown; for although frequently truth does not so greatly affect +our imagination as falsity and fiction, because it seems less +wonderful and is more simple, yet the gratification it affords is +always more durable and solid. The second fruit is, that in studying +these principles we will become accustomed by degrees to judge +better of all the things we come in contact with, and thus be made +wiser, in which respect the effect will be quite the opposite of the +common philosophy, for we may easily remark in those we call pedants +that it renders them less capable of rightly exercising their reason +than they would have been if they had never known it. The third is, +that the truths which they contain, being highly clear and certain, +will take away all ground of dispute, and thus dispose men's minds +to gentleness and concord; whereas the contrary is the effect of the +controversies of the schools, which, as they insensibly render those +who are exercised in them more wrangling and opinionative, are +perhaps the prime cause of the heresies and dissensions that now +harass the world. The last and chief fruit of these Principles is, +that one will be able, by cultivating them, to discover many truths +I myself have not unfolded, and thus passing by degrees from one to +another, to acquire in course of time a perfect knowledge of the +whole of philosophy, and to rise to the highest degree of wisdom. +For just as all the arts, though in their beginnings they are rude +and imperfect, are yet gradually perfected by practice, from their +containing at first something true, and whose effect experience +evinces; so in philosophy, when we have true principles, we cannot +fail by following them to meet sometimes with other truths; and we +could not better prove the falsity of those of Aristotle, than by +saying that men made no progress in knowledge by their means during +the many ages they prosecuted them. + +I well know that there are some men so precipitate and accustomed to +use so little circumspection in what they do, that, even with the +most solid foundations, they could not rear a firm superstructure; +and as it is usually those who are the readiest to make books, they +would in a short time mar all that I have done, and introduce +uncertainty and doubt into my manner of philosophizing, from which I +have carefully endeavoured to banish them, if people were to receive +their writings as mine, or as representing my opinions. I had, not +long ago, some experience of this in one of those who were believed +desirous of following me the most closely, [Footnote: Regius; see La +Vie de M. Descartes, reduite en abrege (Baillet). Liv. vii., chap. +vii.--T.] and one too of whom I had somewhere said that I had such +confidence in his genius as to believe that he adhered to no +opinions which I should not be ready to avow as mine; for he last +year published a book entitled "Fundamental Physics," in which, +although he seems to have written nothing on the subject of Physics +and Medicine which he did not take from my writings, as well from +those I have published as from another still imperfect on the nature +of animals, which fell into his hands; nevertheless, because he has +copied them badly, and changed the order, and denied certain +metaphysical truths upon which all Physics ought to be based, I am +obliged wholly to disavow his work, and here to request readers not +to attribute to me any opinion unless they find it expressly stated +in my own writings, and to receive no opinion as true, whether in my +writings or elsewhere, unless they see that it is very clearly +deduced from true principles. I well know, likewise, that many ages +may elapse ere all the truths deducible from these principles are +evolved out of them, as well because the greater number of such as +remain to be discovered depend on certain particular experiments +that never occur by chance, but which require to be investigated +with care and expense by men of the highest intelligence, as because +it will hardly happen that the same persons who have the sagacity to +make a right use of them, will possess also the means of making +them, and also because the majority of the best minds have formed so +low an estimate of philosophy in general, from the imperfections +they have remarked in the kind in vogue up to the present time, that +they cannot apply themselves to the search after truth. + +But, in conclusion, if the difference discernible between the +principles in question and those of every other system, and the +great array of truths deducible from them, lead them to discern the +importance of continuing the search after these truths, and to +observe the degree of wisdom, the perfection and felicity of life, +to which they are fitted to conduct us, I venture to believe that +there will not be found one who is not ready to labour hard in so +profitable a study, or at least to favour and aid with all his might +those who shall devote themselves to it with success. + +The height of my wishes is, that posterity may sometime behold the +happy issue of it, etc. + + + + +TO THE MOST SERENE PRINCESS, + +ELIZABETH, ELDEST DAUGHTER OF FREDERICK, KING OF BOHEMIA, COUNT +PALATINE, AND ELECTOR OF THE SACRED ROMAN EMPIRE. + +MADAM,--The greatest advantage I have derived from the writings +which I have already published, has arisen from my having, through +means of them, become known to your Highness, and thus been +privileged to hold occasional converse with one in whom so many rare +and estimable qualities are united, as to lead me to believe I +should do service to the public by proposing them as an example to +posterity. It would ill become me to flatter, or to give expression +to anything of which I had no certain knowledge, especially in the +first pages of a work in which I aim at laying down the principles +of truth. And the generous modesty that is conspicuous in all your +actions, assures me that the frank and simple judgment of a man who +only writes what he believes will be more agreeable to you than the +ornate laudations of those who have studied the art of compliment. +For this reason, I will give insertion to nothing in this letter for +which I have not the certainty both of experience and reason; and in +the exordium, as in the rest of the work, I will write only as +becomes a philosopher. There is a vast difference between real and +apparent virtues; and there is also a great discrepancy between +those real virtues that proceed from an accurate knowledge of the +truth, and such as are accompanied with ignorance or error. The +virtues I call apparent are only, properly speaking, vices, which, +as they are less frequent than the vices that are opposed to them, +and are farther removed from them than the intermediate virtues, are +usually held in higher esteem than those virtues. Thus, because +those who fear dangers too much are more numerous than they who fear +them too little, temerity is frequently opposed to the vice of +timidity, and taken for a virtue, and is commonly more highly +esteemed than true fortitude. Thus, also, the prodigal are in +ordinary more praised than the liberal; and none more easily acquire +a great reputation for piety than the superstitious and +hypocritical. With regard to true virtues, these do not all proceed +from true knowledge, for there are some that likewise spring from +defect or error; thus, simplicity is frequently the source of +goodness, fear of devotion, and despair of courage. The virtues that +are thus accompanied with some imperfections differ from each other, +and have received diverse appellations. But those pure and perfect +virtues that arise from the knowledge of good alone are all of the +same nature, and may be comprised under the single term wisdom. For, +whoever owns the firm and constant resolution of always using his +reason as well as lies in his power, and in all his actions of doing +what he judges to be best, is truly wise, as far as his nature +permits; and by this alone he is just, courageous, temperate, and +possesses all the other virtues, but so well balanced as that none +of them appears more prominent than another: and for this reason, +although they are much more perfect than the virtues that blaze +forth through the mixture of some defect, yet, because the crowd +thus observes them less, they are not usually extolled so highly. +Besides, of the two things that are requisite for the wisdom thus +described, namely, the perception of the understanding and the +disposition of the will, it is only that which lies in the will +which all men can possess equally, inasmuch as the understanding of +some is inferior to that of others. But although those who have only +an inferior understanding may be as perfectly wise as their nature +permits, and may render themselves highly acceptable to God by their +virtue, provided they preserve always a firm and constant resolution +to do all that they shall judge to be right, and to omit nothing +that may lead them to the knowledge of the duties of which they are +ignorant; nevertheless, those who preserve a constant resolution of +performing the right, and are especially careful in instructing +themselves, and who possess also a highly perspicacious intellect, +arrive doubtless at a higher degree of wisdom than others; and I see +that these three particulars are found in great perfection in your +Highness. For, in the first place, your desire of self-instruction +is manifest, from the circumstance that neither the amusements of +the court, nor the accustomed mode of educating ladies, which +ordinarily condemns them to ignorance, have been sufficient to +prevent you from studying with much care all that is best in the +arts and sciences; and the incomparable perspicacity of your +intellect is evinced by this, that you penetrated the secrets of the +sciences and acquired an accurate knowledge of them in a very short +period. But of the vigour of your intellect I have a still stronger +proof, and one peculiar to myself, in that I have never yet met any +one who understood so generally and so well as yourself all that is +contained in my writings. For there are several, even among men of +the highest intellect and learning, who find them very obscure. And +I remark, in almost all those who are versant in Metaphysics, that +they are wholly disinclined from Geometry; and, on the other hand, +that the cultivators of Geometry have no ability for the +investigations of the First Philosophy: insomuch that I can say with +truth I know but one mind, and that is your own, to which both +studies are alike congenial, and which I therefore, with propriety, +designate incomparable. But what most of all enhances my admiration +is, that so accurate and varied an acquaintance with the whole +circle of the sciences is not found in some aged doctor who has +employed many years in contemplation, but in a Princess still young, +and whose countenance and years would more fitly represent one of +the Graces than a Muse or the sage Minerva. In conclusion, I not +only remark in your Highness all that is requisite on the part of +the mind to perfect and sublime wisdom, but also all that can be +required on the part of the will or the manners, in which benignity +and gentleness are so conjoined with majesty that, though fortune +has attacked you with continued injustice, it has failed either to +irritate or crush you. And this constrains me to such veneration +that I not only think this work due to you, since it treats of +philosophy which is the study of wisdom, but likewise feel not more +zeal for my reputation as a philosopher than pleasure in subscribing +myself,-- + +Of your most Serene Highness, The most devoted servant, + +DESCARTES. + + + + +PART I. +OF THE PRINCIPLES OF HUMAN KNOWLEDGE. + + + I. THAT in order to seek truth, it is necessary once in the course +of our life, to doubt, as far as possible, of all things. + +As we were at one time children, and as we formed various judgments +regarding the objects presented to our senses, when as yet we had +not the entire use of our reason, numerous prejudices stand in the +way of our arriving at the knowledge of truth; and of these it seems +impossible for us to rid ourselves, unless we undertake, once in our +lifetime, to doubt of all those things in which we may discover even +the smallest suspicion of uncertainty. + + + II. That we ought also to consider as false all that is doubtful. + +Moreover, it will be useful likewise to esteem as false the things +of which we shall be able to doubt, that we may with greater +clearness discover what possesses most certainty and is the easiest +to know. + + + III. That we ought not meanwhile to make use of doubt in the +conduct of life. + +In the meantime, it is to be observed that we are to avail ourselves +of this general doubt only while engaged in the contemplation of +truth. For, as far as concerns the conduct of life, we are very +frequently obliged to follow opinions merely probable, or even +sometimes, though of two courses of action we may not perceive more +probability in the one than in the other, to choose one or other, +seeing the opportunity of acting would not unfrequently pass away +before we could free ourselves from our doubts. + + + IV. Why we may doubt of sensible things. + +Accordingly, since we now only design to apply ourselves to the +investigation of truth, we will doubt, first, whether of all the +things that have ever fallen under our senses, or which we have ever +imagined, any one really exist; in the first place, because we know +by experience that the senses sometimes err, and it would be +imprudent to trust too much to what has even once deceived us; +secondly, because in dreams we perpetually seem to perceive or +imagine innumerable objects which have no existence. And to one who +has thus resolved upon a general doubt, there appear no marks by +which he can with certainty distinguish sleep from the waking state. + + + V. Why we may also doubt of mathematical demonstrations. + +We will also doubt of the other things we have before held as most +certain, even of the demonstrations of mathematics, and of their +principles which we have hitherto deemed self-evident; in the first +place, because we have sometimes seen men fall into error in such +matters, and admit as absolutely certain and self evident what to us +appeared false, but chiefly because we have learnt that God who +created us is all-powerful; for we do not yet know whether perhaps +it was his will to create us so that we are always deceived, even in +the things we think we know best: since this does not appear more +impossible than our being occasionally deceived, which, however, as +observation teaches us, is the case. And if we suppose that an all- +powerful God is not the author of our being, and that we exist of +ourselves or by some other means, still, the less powerful we +suppose our author to be, the greater reason will we have for +believing that we are not so perfect as that we may not be +continually deceived. + + + VI. That we possess a free-will, by which we can withhold our +assent from what is doubtful, and thus avoid error. + +But meanwhile, whoever in the end may be the author of our being, +and however powerful and deceitful he may be, we are nevertheless +conscious of a freedom, by which we can refrain from admitting to a +place in our belief aught that is not manifestly certain and +undoubted, and thus guard against ever being deceived. + + + VII. That we cannot doubt of our existence while we doubt, and that +this is the first knowledge we acquire when we philosophize in +order. + +While we thus reject all of which we can entertain the smallest +doubt, and even imagine that it is false, we easily indeed suppose +that there is neither God, nor sky, nor bodies, and that we +ourselves even have neither hands nor feet, nor, finally, a body; +but we cannot in the same way suppose that we are not while we doubt +of the truth of these things; for there is a repugnance in +conceiving that what thinks does not exist at the very time when it +thinks. Accordingly, the knowledge, _I_ THINK, THEREFORE _I_ AM, is +the first and most certain that occurs to one who philosophizes +orderly. + + + VIII. That we hence discover the distinction between the mind and +the body, or between a thinking and corporeal thing. + +And this is the best mode of discovering the nature of the mind, and +its distinctness from the body: for examining what we are, while +supposing, as we now do, that there is nothing really existing apart +from our thought, we clearly perceive that neither extension, nor +figure, nor local motion,[Footnote: Instead of "local motion," the +French has "existence in any place."] nor anything similar that can +be attributed to body, pertains to our nature, and nothing save +thought alone; and, consequently, that the notion we have of our +mind precedes that of any corporeal thing, and is more certain, +seeing we still doubt whether there is any body in existence, while +we already perceive that we think. + + + IX. What thought (COGITATIO) is. + +By the word thought, I understand all that which so takes place in +us that we of ourselves are immediately conscious of it; and, +accordingly, not only to understand (INTELLIGERE, ENTENDRE), to will +(VELLE), to imagine (IMAGINARI), but even to perceive (SENTIRE, +SENTIR), are here the same as to think (COGITARE, PENSER). For if I +say, I see, or, I walk, therefore I am; and if I understand by +vision or walking the act of my eyes or of my limbs, which is the +work of the body, the conclusion is not absolutely certain, because, +as is often the case in dreams, I may think that I see or walk, +although I do not open my eyes or move from my place, and even, +perhaps, although I have no body: but, if I mean the sensation +itself, or consciousness of seeing or walking, the knowledge is +manifestly certain, because it is then referred to the mind, which +alone perceives or is conscious that it sees or walks. [Footnote: In +the French, "which alone has the power of perceiving, or of being +conscious in any other way whatever."] + + + X. That the notions which are simplest and self-evident, are +obscured by logical definitions; and that such are not to be +reckoned among the cognitions acquired by study, [but as born with +us]. + +I do not here explain several other terms which I have used, or +design to use in the sequel, because their meaning seems to me +sufficiently self-evident. And I frequently remarked that +philosophers erred in attempting to explain, by logical definitions, +such truths as are most simple and self-evident; for they thus only +rendered them more obscure. And when I said that the proposition, +_I_ THINK, THEREFORE _I_ AM, is of all others the first and most +certain which occurs to one philosophizing orderly, I did not +therefore deny that it was necessary to know what thought, +existence, and certitude are, and the truth that, in order to think +it is necessary to be, and the like; but, because these are the most +simple notions, and such as of themselves afford the knowledge of +nothing existing, I did not judge it proper there to enumerate them. + + + XI. How we can know our mind more clearly than our body. + +But now that it may be discerned how the knowledge we have of the +mind not only precedes, and has greater certainty, but is even +clearer, than that we have of the body, it must be remarked, as a +matter that is highly manifest by the natural light, that to nothing +no affections or qualities belong; and, accordingly, that where we +observe certain affections, there a thing or substance to which +these pertain, is necessarily found. The same light also shows us +that we know a thing or substance more clearly in proportion as we +discover in it a greater number of qualities. Now, it is manifest +that we remark a greater number of qualities in our mind than in any +other thing; for there is no occasion on which we know anything +whatever when we are not at the same time led with much greater +certainty to the knowledge of our own mind. For example, if I judge +that there is an earth because I touch or see it, on the same +ground, and with still greater reason, I must be persuaded that my +mind exists; for it may be, perhaps, that I think I touch the earth +while there is one in existence; but it is not possible that I +should so judge, and my mind which thus judges not exist; and the +same holds good of whatever object is presented to our mind. + + + XII. How it happens that every one does not come equally to know +this. + +Those who have not philosophized in order have had other opinions on +this subject, because they never distinguished with sufficient care +the mind from the body. For, although they had no difficulty in +believing that they themselves existed, and that they had a higher +assurance of this than of any other thing, nevertheless, as they did +not observe that by THEMSELVES, they ought here to understand their +MINDS alone [when the question related to metaphysical certainty]; +and since, on the contrary, they rather meant their bodies which +they saw with their eyes, touched with their hands, and to which +they erroneously attributed the faculty of perception, they were +prevented from distinctly apprehending the nature of the mind. + + + XIII. In what sense the knowledge of other things depends upon the +knowledge of God. + +But when the mind, which thus knows itself but is still in doubt as +to all other things, looks around on all sides, with a view to the +farther extension of its knowledge, it first of all discovers within +itself the ideas of many things; and while it simply contemplates +them, and neither affirms nor denies that there is anything beyond +itself corresponding to them, it is in no danger of erring. The mind +also discovers certain common notions out of which it frames various +demonstrations that carry conviction to such a degree as to render +doubt of their truth impossible, so long as we give attention to +them. For example, the mind has within itself ideas of numbers and +figures, and it has likewise among its common notions the principle +THAT IF EQUALS BE ADDED TO EQUALS THE WHOLES WILL BE EQUAL and the +like; from which it is easy to demonstrate that the three angles of +a triangle are equal to two right angles, etc. Now, so long as we +attend to the premises from which this conclusion and others similar +to it were deduced, we feel assured of their truth; but, as the mind +cannot always think of these with attention, when it has the +remembrance of a conclusion without recollecting the order of its +deduction, and is uncertain whether the author of its being has +created it of a nature that is liable to be deceived, even in what +appears most evident, it perceives that there is just ground to +distrust the truth of such conclusions, and that it cannot possess +any certain knowledge until it has discovered its author. + + + XIV. That we may validly infer the existence of God from necessary +existence being comprised in the concept we have of him. + +When the mind afterwards reviews the different ideas that are in it, +it discovers what is by far the chief among them--that of a Being +omniscient, all-powerful, and absolutely perfect; and it observes +that in this idea there is contained not only possible and +contingent existence, as in the ideas of all other things which it +clearly perceives, but existence absolutely necessary and eternal. +And just as because, for example, the equality of its three angles +to two right angles is necessarily comprised in the idea of a +triangle, the mind is firmly persuaded that the three angles of a +triangle are equal to two right angles; so, from its perceiving +necessary and eternal existence to be comprised in the idea which it +has of an all-perfect Being, it ought manifestly to conclude that +this all-perfect Being exists. + + + XV. That necessary existence is not in the same way comprised in +the notions which we have of other things, but merely contingent +existence. + +The mind will be still more certain of the truth of this conclusion, +if it consider that it has no idea of any other thing in which it +can discover that necessary existence is contained; for, from this +circumstance alone, it will discern that the idea of an all-perfect +Being has not been framed by itself, and that it does not represent +a chimera, but a true and immutable nature, which must exist since +it can only be conceived as necessarily existing. + + + XVI. That prejudices hinder many from clearly knowing the necessity +of the existence of God. + +Our mind would have no difficulty in assenting to this truth, if it +were, first of all, wholly free from prejudices; but as we have been +accustomed to distinguish, in all other things, essence from +existence, and to imagine at will many ideas of things which neither +are nor have been, it easily happens, when we do not steadily fix +our thoughts on the contemplation of the all-perfect Being, that a +doubt arises as to whether the idea we have of him is not one of +those which we frame at pleasure, or at least of that class to whose +essence existence does not pertain. + + + XVII. That the greater objective (representative) perfection there +is in our idea of a thing, the greater also must be the perfection +of its cause. + +When we further reflect on the various ideas that are in us, it is +easy to perceive that there is not much difference among them, when +we consider them simply as certain modes of thinking, but that they +are widely different, considered in reference to the objects they +represent; and that their causes must be so much the more perfect +according to the degree of objective perfection contained in them. +[Footnote: "as what they represent of their object has more +perfection."--FRENCH.] For there is no difference between this and +the case of a person who has the idea of a machine, in the +construction of which great skill is displayed, in which +circumstances we have a right to inquire how he came by this idea, +whether, for example, he somewhere saw such a machine constructed by +another, or whether he was so accurately taught the mechanical +sciences, or is endowed with such force of genius, that he was able +of himself to invent it, without having elsewhere seen anything like +it; for all the ingenuity which is contained in the idea objectively +only, or as it were in a picture, must exist at least in its first +and chief cause, whatever that may be, not only objectively or +representatively, but in truth formally or eminently. + + + XVIII. That the existence of God may be again inferred from the +above. + +Thus, because we discover in our minds the idea of God, or of an +all-perfect Being, we have a right to inquire into the source whence +we derive it; and we will discover that the perfections it +represents are so immense as to render it quite certain that we +could only derive it from an all-perfect Being; that is, from a God +really existing. For it is not only manifest by the natural light +that nothing cannot be the cause of anything whatever, and that the +more perfect cannot arise from the less perfect, so as to be thereby +produced as by its efficient and total cause, but also that it is +impossible we can have the idea or representation of anything +whatever, unless there be somewhere, either in us or out of us, an +original which comprises, in reality, all the perfections that are +thus represented to us; but, as we do not in any way find in +ourselves those absolute perfections of which we have the idea, we +must conclude that they exist in some nature different from ours, +that is, in God, or at least that they were once in him; and it most +manifestly follows [from their infinity] that they are still there. + + + XIX. That, although we may not comprehend the nature of God, there +is yet nothing which we know so clearly as his perfections. + +This will appear sufficiently certain and manifest to those who have +been accustomed to contemplate the idea of God, and to turn their +thoughts to his infinite perfections; for, although we may not +comprehend them, because it is of the nature of the infinite not to +be comprehended by what is finite, we nevertheless conceive them +more clearly and distinctly than material objects, for this reason, +that, being simple, and unobscured by limits,[Footnote: After +LIMITS, "what of them we do conceive is much less confused. There +is, besides, no speculation more calculated to aid in perfecting our +understanding, and which is more important than this, inasmuch as +the consideration of an object that has no limits to its perfections +fills us with satisfaction and assurance."-FRENCH.] they occupy our +mind more fully. + + + XX. That we are not the cause of ourselves, but that this is God, +and consequently that there is a God. + +But, because every one has not observed this, and because, when we +have an idea of any machine in which great skill is displayed, we +usually know with sufficient accuracy the manner in which we +obtained it, and as we cannot even recollect when the idea we have +of a God was communicated to us by him, seeing it was always in our +minds, it is still necessary that we should continue our review, and +make inquiry after our author, possessing, as we do, the idea of the +infinite perfections of a God: for it is in the highest degree +evident by the natural light, that that which knows something more +perfect than itself, is not the source of its own being, since it +would thus have given to itself all the perfections which it knows; +and that, consequently, it could draw its origin from no other being +than from him who possesses in himself all those perfections, that +is, from God. + + + XXI. That the duration alone of our life is sufficient to +demonstrate the existence of God. + +The truth of this demonstration will clearly appear, provided we +consider the nature of time, or the duration of things; for this is +of such a kind that its parts are not mutually dependent, and never +co-existent; and, accordingly, from the fact that we now are, it +does not necessarily follow that we shall be a moment afterwards, +unless some cause, viz., that which first produced us, shall, as it +were, continually reproduce us, that is, conserve us. For we easily +understand that there is no power in us by which we can conserve +ourselves, and that the being who has so much power as to conserve +us out of himself, must also by so much the greater reason conserve +himself, or rather stand in need of being conserved by no one +whatever, and, in fine, be God. + + + XXII. That in knowing the existence of God, in the manner here +explained, we likewise know all his attributes, as far as they can +be known by the natural light alone. + +There is the great advantage in proving the existence of God in this +way, viz., by his idea, that we at the same time know what he is, as +far as the weakness of our nature allows; for, reflecting on the +idea we have of him which is born with us, we perceive that he is +eternal, omniscient, omnipotent, the source of all goodness and +truth, creator of all things, and that, in fine, he has in himself +all that in which we can clearly discover any infinite perfection or +good that is not limited by any imperfection. + + + XXIII. That God is not corporeal, and does not perceive by means of +senses as we do, or will the evil of sin. + +For there are indeed many things in the world that are to a certain +extent imperfect or limited, though possessing also some perfection; +and it is accordingly impossible that any such can be in God. Thus, +looking to corporeal nature,[Footnote: In the French, "since +extension constitutes the nature of body."] since divisibility is +included in local extension, and this indicates imperfection, it is +certain that God is not body. And although in men it is to some +degree a perfection to be capable of perceiving by means of the +senses, nevertheless since in every sense there is passivity +[Footnote: In the French, "because our perceptions arise from +impressions made upon us from another source," i.e., than +ourselves.] which indicates dependency, we must conclude that God is +in no manner possessed of senses, and that he only understands and +wills, not, however, like us, by acts in any way distinct, but +always by an act that is one, identical, and the simplest possible, +understands, wills, and operates all, that is, all things that in +reality exist; for he does not will the evil of sin, seeing this is +but the negation of being. + + + XXIV. That in passing from the knowledge of God to the knowledge of +the creatures, it is necessary to remember that our understanding is +finite, and the power of God infinite. + +But as we know that God alone is the true cause of all that is or +can be, we will doubtless follow the best way of philosophizing, if, +from the knowledge we have of God himself, we pass to the +explication of the things which he has created, and essay to deduce +it from the notions that are naturally in our minds, for we will +thus obtain the most perfect science, that is, the knowledge of +effects through their causes. But that we may be able to make this +attempt with sufficient security from error, we must use the +precaution to bear in mind as much as possible that God, who is the +author of things, is infinite, while we are wholly finite. + + + XXV. That we must believe all that God has revealed, although it +may surpass the reach of our faculties. + +Thus, if perhaps God reveal to us or others, matters concerning +himself which surpass the natural powers of our mind, such as the +mysteries of the incarnation and of the trinity, we will not refuse +to believe them, although we may not clearly understand them; nor +will we be in any way surprised to find in the immensity of his +nature, or even in what he has created, many things that exceed our +comprehension. + + + XXVI. That it is not needful to enter into disputes [Footnote: "to +essay to comprehend the infinite."--FRENCH.] regarding the infinite, +but merely to hold all that in which we can find no limits as +indefinite, such as the extension of the world, the divisibility of +the parts of matter, the number of the stars, etc. + +We will thus never embarrass ourselves by disputes about the +infinite, seeing it would be absurd for us who are finite to +undertake to determine anything regarding it, and thus as it were to +limit it by endeavouring to comprehend it. We will accordingly give +ourselves no concern to reply to those who demand whether the half +of an infinite line is also infinite, and whether an infinite number +is even or odd, and the like, because it is only such as imagine +their minds to be infinite who seem bound to entertain questions of +this sort. And, for our part, looking to all those things in which +in certain senses, we discover no limits, we will not, therefore, +affirm that they are infinite, but will regard them simply as +indefinite. Thus, because we cannot imagine extension so great that +we cannot still conceive greater, we will say that the magnitude of +possible things is indefinite, and because a body cannot be divided +into parts so small that each of these may not be conceived as again +divided into others still smaller, let us regard quantity as +divisible into parts whose number is indefinite; and as we cannot +imagine so many stars that it would seem impossible for God to +create more, let us suppose that their number is indefinite, and so +in other instances. + + + XXVII. What difference there is between the indefinite and the +infinite. + +And we will call those things indefinite rather than infinite, with +the view of reserving to God alone the appellation of infinite; in +the first place, because not only do we discover in him alone no +limits on any side, but also because we positively conceive that he +admits of none; and in the second place, because we do not in the +same way positively conceive that other things are in every part +unlimited, but merely negatively admit that their limits, if they +have any, cannot be discovered by us. + + + XXVIII. That we must examine, not the final, but the efficient, +causes of created things. + +Likewise, finally, we will not seek reasons of natural things from +the end which God or nature proposed to himself in their creation +(i. e., final causes), [Footnote: "We will not stop to consider the +ends which God proposed to himself in the creation of the world, and +we will entirely reject from our philosophy the search of final +causes!"--French.] for we ought not to presume so far as to think +that we are sharers in the counsels of Deity, but, considering him +as the efficient cause of all things, let us endeavour to discover +by the natural light [Footnote: "Faculty of reasoning."--FRENCH.] +which he has planted in us, applied to those of his attributes of +which he has been willing we should have some knowledge, what must +be concluded regarding those effects we perceive by our senses; +bearing in mind, however, what has been already said, that we must +only confide in this natural light so long as nothing contrary to +its dictates is revealed by God himself. [Footnote: The last clause, +beginning "bearing in mind." is omitted in the French.] + + + XXIX. That God is not the cause of our errors. + +The first attribute of God which here falls to be considered, is +that he is absolutely veracious and the source of all light, so that +it is plainly repugnant for him to deceive us, or to be properly and +positively the cause of the errors to which we are consciously +subject; for although the address to deceive seems to be some mark +of subtlety of mind among men, yet without doubt the will to deceive +only proceeds from malice or from fear and weakness, and +consequently cannot be attributed to God. + + + XXX. That consequently all which we clearly perceive is true, and +that we are thus delivered from the doubts above proposed. + +Whence it follows, that the light of nature, or faculty of knowledge +given us by God, can never compass any object which is not true, in +as far as it attains to a knowledge of it, that is, in as far as the +object is clearly and distinctly apprehended. For God would have +merited the appellation of a deceiver if he had given us this +faculty perverted, and such as might lead us to take falsity for +truth [when we used it aright]. Thus the highest doubt is removed, +which arose from our ignorance on the point as to whether perhaps +our nature was such that we might be deceived even in those things +that appear to us the most evident. The same principle ought also to +be of avail against all the other grounds of doubting that have been +already enumerated. For mathematical truths ought now to be above +suspicion, since these are of the clearest. And if we perceive +anything by our senses, whether while awake or asleep, we will +easily discover the truth provided we separate what there is of +clear and distinct in the knowledge from what is obscure and +confused. There is no need that I should here say more on this +subject, since it has already received ample treatment in the +metaphysical Meditations; and what follows will serve to explain it +still more accurately. + + + XXXI. That our errors are, in respect of God, merely negations, +but, in respect of ourselves, privations. + +But as it happens that we frequently fall into error, although God +is no deceiver, if we desire to inquire into the origin and cause of +our errors, with a view to guard against them, it is necessary to +observe that they depend less on our understanding than on our will, +and that they have no need of the actual concourse of God, in order +to their production; so that, when considered in reference to God, +they are merely negations, but in reference to ourselves, +privations. + + + XXXII. That there are only two modes of thinking in us, viz., the +perception of the understanding and the action of the will. + +For all the modes of thinking of which we are conscious may be +referred to two general classes, the one of which is the perception +or operation of the understanding, and the other the volition or +operation of the will. Thus, to perceive by the senses (SENTIRE), to +imagine, and to conceive things purely intelligible, are only +different modes of perceiving (PERCIP IENDI); but to desire, to be +averse from, to affirm, to deny, to doubt, are different modes of +willing. + + + XXXIII. That we never err unless when we judge of something which +we do not sufficiently apprehend. + +When we apprehend anything we are in no danger of error, if we +refrain from judging of it in any way; and even when we have formed +a judgment regarding it, we would never fall into error, provided we +gave our assent only to what we clearly and distinctly perceived; +but the reason why we are usually deceived, is that we judge without +possessing an exact knowledge of that of which we judge. + + + XXXIV. That the will as well as the understanding is required for +judging. + +I admit that the understanding is necessary for judging, there being +no room to suppose that we can judge of that which we in no way +apprehend; but the will also is required in order to our assenting +to what we have in any degree perceived. It is not necessary, +however, at least to form any judgment whatever, that we have an +entire and perfect apprehension of a thing; for we may assent to +many things of which we have only a very obscure and confused +knowledge. + + + XXXV. That the will is of greater extension than the understanding, +and is thus the source of our errors. + +Further, the perception of the intellect extends only to the few +things that are presented to it, and is always very limited: the +will, on the other hand, may, in a certain sense, be said to be +infinite, because we observe nothing that can be the object of the +will of any other, even of the unlimited will of God, to which ours +cannot also extend, so that we easily carry it beyond the objects we +clearly perceive; and when we do this, it is not wonderful that we +happen to be deceived. + + + XXXVI. That our errors cannot be imputed to God. + +But although God has not given us an omniscient understanding, he is +not on this account to be considered in any wise the author of our +errors, for it is of the nature of created intellect to be finite, +and of finite intellect not to embrace all things. + + + XXXVII. That the chief perfection of man is his being able to act +freely or by will, and that it is this which renders him worthy of +praise or blame. + +That the will should be the more extensive is in harmony with its +nature: and it is a high perfection in man to be able to act by +means of it, that is, freely; and thus in a peculiar way to be the +master of his own actions, and merit praise or blame. For self- +acting machines are not commended because they perform with +exactness all the movements for which they were adapted, seeing +their motions are carried on necessarily; but the maker of them is +praised on account of the exactness with which they were framed, +because he did not act of necessity, but freely; and, on the same +principle, we must attribute to ourselves something more on this +account, that when we embrace truth, we do so not of necessity, but +freely. + + + XXXVIII. That error is a defect in our mode of acting, not in our +nature; and that the faults of their subjects may be frequently +attributed to other masters, but never to God. + +It is true, that as often as we err, there is some defect in our +mode of action or in the use of our liberty, but not in our nature, +because this is always the same, whether our judgments be true or +false. And although God could have given to us such perspicacity of +intellect that we should never have erred, we have, notwithstanding, +no right to demand this of him; for, although with us he who was +able to prevent evil and did not is held guilty of it, God is not in +the same way to be reckoned responsible for our errors because he +had the power to prevent them, inasmuch as the dominion which some +men possess over others has been instituted for the purpose of +enabling them to hinder those under them from doing evil, whereas +the dominion which God exercises over the universe is perfectly +absolute and free. For this reason we ought to thank him for the +goods he has given us, and not complain that he has not blessed us +with all which we know it was in his power to impart. + + + XXXIX. That the liberty of our will is self-evident. + +Finally, it is so manifest that we possess a free will, capable of +giving or withholding its assent, that this truth must be reckoned +among the first and most common notions which are born with us. +This, indeed, has already very clearly appeared, for when essaying +to doubt of all things, we went so far as to suppose even that he +who created us employed his limitless power in deceiving us in every +way, we were conscious nevertheless of being free to abstain from +believing what was not in every respect certain and undoubted. But +that of which we are unable to doubt at such a time is as self- +evident and clear as any thing we can ever know. + + + XL. That it is likewise certain that God has fore-ordained all +things. + +But because what we have already discovered of God, gives us the +assurance that his power is so immense that we would sin in thinking +ourselves capable of ever doing anything which he had not ordained +beforehand, we should soon be embarrassed in great difficulties if +we undertook to harmonise the pre-ordination of God with the freedom +of our will, and endeavoured to comprehend both truths at once. + + + XLI. How the freedom of our will may be reconciled with the Divine +pre-ordination. + +But, in place of this, we will be free from these embarrassments if +we recollect that our mind is limited, while the power of God, by +which he not only knew from all eternity what is or can be, but also +willed and pre-ordained it, is infinite. It thus happens that we +possess sufficient intelligence to know clearly and distinctly that +this power is in God, but not enough to comprehend how he leaves the +free actions of men indeterminate} and, on the other hand, we have +such consciousness of the liberty and indifference which exists in +ourselves, that there is nothing we more clearly or perfectly +comprehend: [so that the omnipotence of God ought not to keep us +from believing it]. For it would be absurd to doubt of that of which +we are fully conscious, and which we experience as existing in +ourselves, because we do not comprehend another matter which, from +its very nature, we know to be incomprehensible. + + + XLII. How, although we never will to err, it is nevertheless by our +will that we do err. + +But now since we know that all our errors depend upon our will, and +as no one wishes to deceive himself, it may seem wonderful that +there is any error in our judgments at all. It is necessary to +remark, however, that there is a great difference between willing to +be deceived, and willing to yield assent to opinions in which it +happens that error is found. For though there is no one who +expressly wishes to fall into error, we will yet hardly find any one +who is not ready to assent to things in which, unknown to himself, +error lurks; and it even frequently happens that it is the desire +itself of following after truth that leads those not fully aware of +the order in which it ought to be sought for, to pass judgment on +matters of which they have no adequate knowledge, and thus to fall +into error. + + + XLIII. That we shall never err if we give our assent only to what +we clearly and distinctly perceive. + +But it is certain we will never admit falsity for truth, so long as +we judge only of that which we clearly and distinctly perceive; +because, as God is no deceiver, the faculty of knowledge which he +has given us cannot be fallacious, nor, for the same reason, the +faculty of will, when we do not extend it beyond the objects we +clearly know. And even although this truth could not be established +by reasoning, the minds of all have been so impressed by nature as +spontaneously to assent to whatever is clearly perceived, and to +experience an impossibility to doubt of its truth. + + + XLIV. That we uniformly judge improperly when we assent to what we +do not clearly perceive, although our judgment may chance to be +true; and that it is frequently our memory which deceives us by +leading us to believe that certain things were formerly sufficiently +understood by us. + +It is likewise certain that, when we approve of any reason which we +do not apprehend, we are either deceived, or, if we stumble on the +truth, it is only by chance, and thus we can never possess the +assurance that we are not in error. I confess it seldom happens that +we judge of a thing when we have observed we do not apprehend it, +because it is a dictate of the natural light never to judge of what +we do not know. But we most frequently err in this, that we presume +upon a past knowledge of much to which we give our assent, as to +something treasured up in the memory, and perfectly known to us; +whereas, in truth, we have no such knowledge. + + + XLV. What constitutes clear and distinct perception. + +There are indeed a great many persons who, through their whole +lifetime, never perceive anything in a way necessary for judging of +it properly; for the knowledge upon which we can establish a certain +and indubitable judgment must be not only clear, but also, distinct. +I call that clear which is present and manifest to the mind giving +attention to it, just as we are said clearly to see objects when, +being present to the eye looking on, they stimulate it with +sufficient force. and it is disposed to regard them; but the +distinct is that which is so precise and different from all other +objects as to comprehend in itself only what is clear. [Footnote: +"what appears manifestly to him who considers it as he ought."-- +FRENCH.] + + + XLVI. It is shown, from the example of pain, that a perception may +be clear without being distinct, but that it cannot be distinct +unless it is clear. + +For example, when any one feels intense pain, the knowledge which he +has of this pain is very clear, but it is not always distinct; for +men usually confound it with the obscure judgment they form +regarding its nature, and think that there is in the suffering part +something similar to the sensation of pain of which they are alone +conscious. And thus perception may be clear without being distinct, +but it can never be distinct without likewise being clear. + + + XLVII. That, to correct the prejudices of our early years, we must +consider what is clear in each of our simple [Footnote: "first."-- +FRENCH.] notions. + +And, indeed, in our early years, the mind was so immersed in the +body, that, although it perceived many things with sufficient +clearness, it yet knew nothing distinctly; and since even at that +time we exercised our judgment in many matters, numerous prejudices +were thus contracted, which, by the majority, are never afterwards +laid aside. But that we may now be in a position to get rid of +these, I will here briefly enumerate all the simple notions of which +our thoughts are composed, and distinguish in each what is clear +from what is obscure, or fitted to lead into error. + + + XLVIII. That all the objects of our knowledge are to be regarded +either (1) as things or the affections of things: or (2) as eternal +truths; with the enumeration of things. + +Whatever objects fall under our knowledge we consider either as +things or the affections of things,[Footnote: Things and the +affections of things are (in the French) equivalent to "what has +some (i.e., a REAL) existence," as opposed to the class of "eternal +truths," which have merely an IDEAL existence.] or as eternal truths +possessing no existence beyond our thought. Of the first class the +most general are substance, duration, order, number, and perhaps +also some others, which notions apply to all the kinds of things. I +do not, however, recognise more than two highest kinds (SUMMA +GENERA) of things; the first of intellectual things, or such as have +the power of thinking, including mind or thinking substance and its +properties; the second, of material things, embracing extended +substance, or body and its properties. Perception, volition, and all +modes as well of knowing as of willing, are related to thinking +substance; on the other hand, to extended substance we refer +magnitude, or extension in length, breadth, and depth, figure, +motion, situation, divisibility of parts themselves, and the like. +There are, however, besides these, certain things of which we have +an internal experience that ought not to be referred either to the +mind of itself, or to the body alone, but to the close and intimate +union between them, as will hereafter be shown in its place. Of this +class are the appetites of hunger and thirst, etc., and also the +emotions or passions of the mind which are not exclusively mental +affections, as the emotions of anger, joy, sadness, love, etc.; and, +finally, all the sensations, as of pain, titillation, light and +colours, sounds, smells, tastes, heat, hardness, and the other +tactile qualities. + + + XLIX. That the eternal truths cannot be thus enumerated, but that +this is not necessary. + +What I have already enumerated we are to regard as things, or the +qualities or modes of things. We now come to speak of eternal +truths. When we apprehend that it is impossible a thing can arise +from nothing, this proposition, EX NIHILO NIHIL FIT, is not +considered as somewhat existing, or as the mode of a thing, but as +an eternal truth having its seat in our mind, and is called a common +notion or axiom. Of this class are the following:--It is impossible +the same thing can at once be and not be; what is done cannot be +undone; he who thinks must exist while he thinks; and innumerable +others, the whole of which it is indeed difficult to enumerate, but +this is not necessary, since, if blinded by no prejudices, we cannot +fail to know them when the occasion of thinking them occurs. + + + L. That these truths are clearly perceived, but not equally by all +men, on account of prejudices. + +And, indeed, with regard to these common notions, it is not to be +doubted that they can be clearly and distinctly known, for otherwise +they would not merit this appellation: as, in truth, some of them +are not, with respect to all men, equally deserving of the name, +because they are not equally admitted by all: not, however, from +this reason, as I think, that the faculty of knowledge of one man +extends farther than that of another, but rather because these +common notions are opposed to the prejudices of some, who, on this +account, are not able readily to embrace them, even although others, +who are free from those prejudices, apprehend them with the greatest +clearness. + + + LI. What substance is, and that the term is not applicable to God +and the creatures in the same sense. + +But with regard to what we consider as things or the modes of +things, it is worth while to examine each of them by itself. By +substance we can conceive nothing else than a thing which exists in +such a way as to stand in need of nothing beyond itself in order to +its existence. And, in truth, there can be conceived but one +substance which is absolutely independent, and that is God. We +perceive that all other things can exist only by help of the +concourse of God. And, accordingly, the term substance does not +apply to God and the creatures UNIVOCALLY, to adopt a term familiar +in the schools; that is, no signification of this word can be +distinctly understood which is common to God and them. + + + LII. That the term is applicable univocally to the mind and the +body, and how substance itself is known. + +Created substances, however, whether corporeal or thinking, may be +conceived under this common concept; for these are things which, in +order to their existence, stand in need of nothing but the concourse +of God. But yet substance cannot be first discovered merely from its +being a thing which exists independently, for existence by itself is +not observed by us. We easily, however, discover substance itself +from any attribute of it, by this common notion, that of nothing +there are no attributes, properties, or qualities: for, from +perceiving that some attribute is present, we infer that some +existing thing or substance to which it may be attributed is also of +necessity present. + + + LIII. That of every substance there is one principal attribute, as +thinking of the mind, extension of the body. + +But, although any attribute is sufficient to lead us to the +knowledge of substance, there is, however, one principal property of +every substance, which constitutes its nature or essence, and upon +which all the others depend. Thus, extension in length, breadth, and +depth, constitutes the nature of corporeal substance; and thought +the nature of thinking substance. For every other thing that can be +attributed to body, presupposes extension, and is only some mode of +an extended thing; as all the properties we discover in the mind are +only diverse modes of thinking. Thus, for example, we cannot +conceive figure unless in something extended, nor motion unless in +extended space, nor imagination, sensation, or will, unless in a +thinking thing. But, on the other hand, we can conceive extension +without figure or motion, and thought without imagination or +sensation, and so of the others; as is clear to any one who attends +to these matters. + + + LIV. How we may have clear and distinct notions of the substance +which thinks, of that which is corporeal, and of God. + +And thus we may easily have two clear and distinct notions or ideas, +the one of created substance, which thinks, the other of corporeal +substance, provided we carefully distinguish all the attributes of +thought from those of extension. We may also have a clear and +distinct idea of an uncreated and independent thinking substance, +that is, of God, provided we do not suppose that this idea +adequately represents to us all that is in God, and do not mix up +with it anything fictitious, but attend simply to the characters +that are comprised in the notion we have of him, and which we +clearly know to belong to the nature of an absolutely perfect Being. +For no one can deny that there is in us such an idea of God, without +groundlessly supposing that there is no knowledge of God at all in +the human mind. + + + LV. How duration, order, and number may be also distinctly +conceived. + +We will also have most distinct conceptions of duration, order, and +number, if, in place of mixing up with our notions of them that +which properly belongs to the concept of substance, we merely think +that the duration of a thing is a mode under which we conceive this +thing, in so far as it continues to exist; and, in like manner, that +order and number are not in reality different from things disposed +in order and numbered, but only modes under which we diversely +consider these things. + + + LVI. What are modes, qualities, attributes. + +And, indeed, we here understand by modes the same with what we +elsewhere designate attributes or qualities. But when we consider +substance as affected or varied by them, we use the term modes; when +from this variation it may be denominated of such a kind, we adopt +the term qualities [to designate the different modes which cause it +to be so named]; and, finally, when we simply regard these modes as +in the substance, we call them attributes. Accordingly, since God +must be conceived as superior to change, it is not proper to say +that there are modes or qualities in him, but simply attributes; and +even in created things that which is found in them always in the +same mode, as existence and duration in the thing which exists and +endures, ought to be called attribute and not mode or quality. + + + LVII. That some attributes exist in the things to which they are +attributed, and others only in our thought; and what duration and +time are. + +Of these attributes or modes there are some which exist in the +things themselves, and others that have only an existence in our +thought; thus, for example, time, which we distinguish from duration +taken in its generality, and call the measure of motion, is only a +certain mode under which we think duration itself, for we do not +indeed conceive the duration of things that are moved to be +different from the duration of things that are not moved: as is +evident from this, that if two bodies are in motion for an hour, the +one moving quickly and the other slowly, we do not reckon more time +in the one than in the other, although there may be much more motion +in the one of the bodies than in the other. But that we may +comprehend the duration of all things under a common measure, we +compare their duration with that of the greatest and most regular +motions that give rise to years and days, and which we call time; +hence what is so designated is nothing superadded to duration, taken +in its generality, but a mode of thinking. + + + LVIII. That number and all universals are only modes of thought. + +In the same way number, when it is not considered as in created +things, but merely in the abstract or in general, is only a mode of +thinking; and the same is true of all those general ideas we call +universals. + + + LIX. How universals are formed; and what are the five common, viz., +genus, species, difference, property, and accident. + +Universals arise merely from our making use of one and the same idea +in thinking of all individual objects between which there subsists a +certain likeness; and when we comprehend all the objects represented +by this idea under one name, this term likewise becomes universal. +For example, when we see two stones, and do not regard their nature +farther than to remark that there are two of them, we form the idea +of a certain number, which we call the binary; and when we +afterwards see two birds or two trees, and merely take notice of +them so far as to observe that there are two of them, we again take +up the same idea as before, which is, accordingly, universal; and we +likewise give to this number the same universal appellation of +binary. In the same way, when we consider a figure of three sides, +we form a certain idea, which we call the idea of a triangle, and we +afterwards make use of it as the universal to represent to our mind +all other figures of three sides. But when we remark more +particularly that of figures of three sides, some have a right angle +and others not, we form the universal idea of a right-angled +triangle, which being related to the preceding as more general, may +be called species; and the right angle the universal difference by +which right-angled triangles are distinguished from all others; and +farther, because the square of the side which sustains the right +angle is equal to the squares of the other two sides, and because +this property belongs only to this species of triangles, we may call +it the universal property of the species. Finally, if we suppose +that of these triangles some are moved and others not, this will be +their universal accident; and, accordingly, we commonly reckon five +universals, viz., genus, species, difference, property, accident. + + + LX. Of distinctions; and first of the real. + +But number in things themselves arises from the distinction there is +between them: and distinction is threefold, viz., real, modal, and +of reason. The real properly subsists between two or more +substances; and it is sufficient to assure us that two substances +are really mutually distinct, if only we are able clearly and +distinctly to conceive the one of them without the other. For the +knowledge we have of God renders it certain that he can effect all +that of which we have a distinct idea: wherefore, since we have now, +for example, the idea of an extended and corporeal substance, though +we as yet do not know with certainty whether any such thing is +really existent, nevertheless, merely because we have the idea of +it, we may be assured that such may exist; and, if it really exists, +that every part which we can determine by thought must be really +distinct from the other parts of the same substance. In the same +way, since every one is conscious that he thinks, and that he in +thought can exclude from himself every other substance, whether +thinking or extended, it is certain that each of us thus considered +is really distinct from every other thinking and corporeal +substance. And although we suppose that God united a body to a soul +so closely that it was impossible to form a more intimate union, and +thus made a composite whole, the two substances would remain really +distinct, notwithstanding this union; for with whatever tie God +connected them, he was not able to rid himself of the power he +possessed of separating them, or of conserving the one apart from +the other, and the things which God can separate or conserve +separately are really distinct. + + + LXI. Of the modal distinction. + +There are two kinds of modal distinctions, viz., that between the +mode properly so-called and the substance of which it is a mode, and +that between two modes of the same substance. Of the former we have +an example in this, that we can clearly apprehend substance apart +from the mode which we say differs from it; while, on the other +hand, we cannot conceive this mode without conceiving the substance +itself. There is, for example, a modal distinction between figure or +motion and corporeal substance in which both exist; there is a +similar distinction between affirmation or recollection and the +mind. Of the latter kind we have an illustration in our ability to +recognise the one of two modes apart from the other, as figure apart +from motion, and motion apart from figure; though we cannot think of +either the one or the other without thinking of the common substance +in which they adhere. If, for example, a stone is moved, and is +withal square, we can, indeed, conceive its square figure without +its motion, and reciprocally its motion without its square figure; +but we can conceive neither this motion nor this figure apart from +the substance of the stone. As for the distinction according to +which the mode of one substance is different from another substance, +or from the mode of another substance, as the motion of one body is +different from another body or from the mind, or as motion is +different from doubt, it seems to me that it should be called real +rather than modal, because these modes cannot be clearly conceived +apart from the really distinct substances of which they are the +modes. + + + LXII. Of the distinction of reason (logical distinction). + +Finally, the distinction of reason is that between a substance and +some one of its attributes, without which it is impossible, however, +we can have a distinct conception of the substance itself; or +between two such attributes of a common substance, the one of which +we essay to think without the other. This distinction is manifest +from our inability to form a clear and distinct idea of such +substance, if we separate from it such attribute; or to have a clear +perception of the one of two such attributes if we separate it from +the other. For example, because any substance which ceases to endure +ceases also to exist, duration is not distinct from substance except +in thought (RATIONE); and in general all the modes of thinking which +we consider as in objects differ only in thought, as well from the +objects of which they are thought as from each other in a common +object.[Footnote: "and generally all the attributes that lead us to +entertain different thoughts of the same thing, such as, for +example, the extension of body and its property of divisibility, do +not differ from the body which is to us the object of them, or from +each other, unless as we sometimes confusedly think the one without +thinking the other."--FRENCH.] It occurs, indeed, to me that I have +elsewhere classed this kind of distinction with the modal (viz., +towards the end of the Reply to the First Objections to the +Meditations on the First Philosophy); but there it was only +necessary to treat of these distinctions generally, and it was +sufficient for my purpose at that time simply to distinguish both of +them from the real. + + + LXIII. How thought and extension may be distinctly known, as +constituting, the one the nature of mind, the other that of body. + +Thought and extension may be regarded as constituting the natures of +intelligent and corporeal substance; and then they must not be +otherwise conceived than as the thinking and extended substances +themselves, that is, as mind and body, which in this way are +conceived with the greatest clearness and distinctness. Moreover, we +more easily conceive extended or thinking substance than substance +by itself, or with the omission of its thinking or extension. For +there is some difficulty in abstracting the notion of substance from +the notions of thinking and extension, which, in truth, are only +diverse in thought itself (i.e., logically different); and a concept +is not more distinct because it comprehends fewer properties, but +because we accurately distinguish what is comprehended in it from +all other notions. + + + LXIV. How these may likewise be distinctly conceived as modes of +substance. + +Thought and extension may be also considered as modes of substance; +in as far, namely, as the same mind may have many different +thoughts, and the same body, with its size unchanged, may be +extended in several diverse ways, at one time more in length and +less in breadth or depth, and at another time more in breadth and +less in length; and then they are modally distinguished from +substance, and can be conceived not less clearly and distinctly, +provided they be not regarded as substances or things separated from +others, but simply as modes of things. For by regarding them as in +the substances of which they are the modes, we distinguish them from +these substances, and take them for what in truth they are: whereas, +on the other hand, if we wish to consider them apart from the +substances in which they are, we should by this itself regard them +as self-subsisting things, and thus confound the ideas of mode and +substance. + + + LXV. How we may likewise know their modes. + +In the same way we will best apprehend the diverse modes of thought, +as intellection, imagination, recollection, volition, etc., and also +the diverse modes of extension, or those that belong to extension, +as all figures, the situation of parts and their motions, provided +we consider them simply as modes of the things in which they are; +and motion as far as it is concerned, provided we think merely of +locomotion, without seeking to know the force that produces it, and +which nevertheless I will essay to explain in its own place. + + + LXVI. How our sensations, affections, and appetites may be clearly +known, although we are frequently wrong in our judgments regarding +them. + +There remain our sensations, affections, and appetites, of which we +may also have a clear knowledge, if we take care to comprehend in +the judgments we form of them only that which is precisely contained +in our perception of them, and of which we are immediately +conscious. There is, however, great difficulty in observing this, at +least in respect of sensations; because we have all, without +exception, from our youth judged that all the things we perceived by +our senses had an existence beyond our thought, and that they were +entirely similar to the sensations, that is, perceptions, we had of +them. Thus when, for example, we saw a certain colour, we thought we +saw something occupying a place out of us, and which was entirely +similar to that idea of colour we were then conscious of; and from +the habit of judging in this way, we seemed to see this so clearly +and distinctly that we esteemed it (i.e., the externality of the +colour) certain and indubitable. + + + LXVII. That we are frequently deceived in our judgments regarding +pain itself. + +The same prejudice has place in all our other sensations, even in +those of titillation and pain. For though we are not in the habit of +believing that there exist out of us objects that resemble +titillation and pain, we do not nevertheless consider these +sensations as in the mind alone, or in our perception, but as in the +hand, or foot, or some other part of our body. There is no reason, +however, to constrain us to believe that the pain, for example, +which we feel, as it were, in the foot is something out of the mind +existing in the foot, or that the light which we see, as it were, in +the sun exists in the sun as it is in us. Both these beliefs are +prejudices of our early years, as will clearly appear in the sequel. + + + LXVIII. How in these things what we clearly conceive is to be +distinguished from that in which we may be deceived. + +But that we may distinguish what is clear in our sensations from +what is obscure, we ought most carefully to observe that we possess +a clear and distinct knowledge of pain, colour, and other things of +this sort, when we consider them simply as sensations or thoughts; +but that, when they are judged to be certain things subsisting +beyond our mind, we are wholly unable to form any conception of +them. Indeed, when any one tells us that he sees colour in a body or +feels pain in one of his limbs, this is exactly the same as if he +said that he there saw or felt something of the nature of which he +was entirely ignorant, or that he did not know what he saw or felt. +For although, when less attentively examining his thoughts, a person +may easily persuade himself that he has some knowledge of it, since +he supposes that there is something resembling that sensation of +colour or of pain of which he is conscious; yet, if he reflects on +what the sensation of colour or pain represents to him as existing +in a coloured body or in a wounded member, he will find that of such +he has absolutely no knowledge. + + + LXIX. That magnitude, figure, etc., are known far differently from +colour, pain, etc. + +What we have said above will be more manifest; especially if we +consider that size in the body perceived, figure, motion (at least +local, for philosophers by fancying other kinds of motion have +rendered its nature less intelligible to themselves), the situation +of parts, duration, number, and those other properties which, as we +have already said, we clearly perceive in all bodies, are known by +us in a way altogether different from that in which we know what +colour is in the same body, or pain, smell, taste, or any other of +those properties which I have said above must be referred to the +senses. For although when we see a body we are not less assured of +its existence from its appearing figured than from its appearing +coloured,[Footnote: "by the colour we perceive on occasion of it."-- +FRENCH.] we yet know with far greater clearness its property of +figure than its colour. + + + LXX. That we may judge of sensible things in two ways, by the one +of which we avoid error, by the other fall into it. + +It is thus manifest that to say we perceive colours in objects is in +reality equivalent to saying we perceive something in objects and +are yet ignorant of what it is, except as that which determines in +us a certain highly vivid and clear sensation, which we call the +sensation of colours. There is, however, very great diversity in the +manner of judging: for so long as we simply judge that there is an +unknown something in objects (that is, in things such as they are, +from which the sensation reached us), so far are we from falling +into error that, on the contrary, we thus rather provide against it, +for we are less apt to judge rashly of a thing which we observe we +do not know. But when we think we perceive colours in objects, +although we are in reality ignorant of what we then denominate +colour, and are unable to conceive any resemblance between the +colour we suppose to be in objects, and that of which we are +conscious in sensation, yet because we do not observe this, or +because there are in objects several properties, as size, figure, +number, etc., which, as we clearly know, exist, or may exist in them +as they are perceived by our senses or conceived by our +understanding, we easily glide into the error of holding that what +is called colour in objects is something entirely resembling the +colour we perceive, and thereafter of supposing that we have a clear +perception of what is in no way perceived by us. + + + LXXI. That the chief cause of our errors is to be found in the +prejudices of our childhood. + +And here we may notice the first and chief cause of our errors. In +early life the mind was so closely bound to the body that it +attended to nothing beyond the thoughts by which it perceived the +objects that made impression on the body; nor as yet did it refer +these thoughts to anything existing beyond itself, but simply felt +pain when the body was hurt, or pleasure when anything beneficial to +the body occurred, or if the body was so highly affected that it was +neither greatly benefited nor hurt, the mind experienced the +sensations we call tastes, smells, sounds, heat, cold, light, +colours, and the like, which in truth are representative of nothing +existing out of our mind, and which vary according to the +diversities of the parts and modes in which the body is affected. +[Footnote: "which vary according to the diversities of the movements +that pass from all parts of our body to the part of the brain to +which it (the mind) is closely joined and united."--FRENCH.] The +mind at the same time also perceived magnitudes, figures, motions, +and the like, which were not presented to it as sensations but as +things or the modes of things existing, or at least capable of +existing out of thought, although it did not yet observe this +difference between these two kinds of perceptions. And afterwards +when the machine of the body, which has been so fabricated by nature +that it can of its own inherent power move itself in various ways, +by turning itself at random on every side, followed after what was +useful and avoided what was detrimental; the mind, which was closely +connected with it, reflecting on the objects it pursued or avoided, +remarked, for the first time, that they existed out of itself, and +not only attributed to them magnitudes, figures, motions, and the +like, which it apprehended either as things or as the modes of +things, but, in addition, attributed to them tastes, odours, and the +other ideas of that sort, the sensations of which were caused by +itself; [Footnote: "which it perceived on occasion of them" (i.e., +of external objects).--FRENCH.] and as it only considered other +objects in so far as they were useful to the body, in which it was +immersed, it judged that there was greater or less reality in each +object, according as the impressions it caused on the body were more +or less powerful. Hence arose the belief that there was more +substance or body in rocks and metals than in air or water, because +the mind perceived in them more hardness and weight. Moreover, the +air was thought to be merely nothing so long as we experienced no +agitation of it by the wind, or did not feel it hot or cold. And +because the stars gave hardly more light than the slender flames of +candles, we supposed that each star was but of this size. Again, +since the mind did not observe that the earth moved on its axis, or +that its superficies was curved like that of a globe, it was on that +account more ready to judge the earth immovable and its surface +flat. And our mind has been imbued from our infancy with a thousand +other prejudices of the same sort which afterwards in our youth we +forgot we had accepted without sufficient examination, and admitted +as possessed of the highest truth and clearness, as if they had been +known by means of our senses, or implanted in us by nature. + + + LXXII. That the second cause of our errors is that we cannot forget +these prejudices. + +And although now in our mature years, when the mind, being no longer +wholly subject to the body, is not in the habit of referring all +things to it, but also seeks to discover the truth of things +considered in themselves, we observe the falsehood of a great many +of the judgments we had before formed; yet we experience a +difficulty in expunging them from our memory, and, so long as they +remain there, they give rise to various errors. Thus, for example, +since from our earliest years we imagined the stars to be of very +small size, we find it highly difficult to rid ourselves of this +imagination, although assured by plain astronomical reasons that +they are of the greatest,--so prevailing is the power of +preconceived opinion. + + + LXXIII. The third cause is, that we become fatigued by attending to +those objects which are not present to the senses; and that we are +thus accustomed to judge of these not from present perception but +from pre-conceived opinion. + +Besides, our mind cannot attend to any object without at length +experiencing some pain and fatigue; and of all objects it has the +greatest difficulty in attending to those which are present neither +to the senses nor to the imagination: whether for the reason that +this is natural to it from its union with the body, or because in +our early years, being occupied merely with perceptions and +imaginations, it has become more familiar with, and acquired greater +facility in thinking in those modes than in any other. Hence it also +happens that many are unable to conceive any substance except what +is imaginable and corporeal, and even sensible. For they are +ignorant of the circumstance, that those objects alone are +imaginable which consist in extension, motion, and figure, while +there are many others besides these that are intelligible; and they +persuade themselves that nothing can subsist but body, and, finally, +that there is no body which is not sensible. And since in truth we +perceive no object such as it is by sense alone [but only by our +reason exercised upon sensible objects], as will hereafter be +clearly shown, it thus happens that the majority during life +perceive nothing unless in a confused way. + + + LXXIV. The fourth source of our errors is, that we attach our +thoughts to words which do not express them with accuracy. + +Finally, since for the use of speech we attach all our conceptions +to words by which to express them, and commit to memory our thoughts +in connection with these terms, and as we afterwards find it more +easy to recall the words than the things signified by them, we can +scarcely conceive anything with such distinctness as to separate +entirely what we conceive from the words that were selected to +express it. On this account the majority attend to words rather than +to things; and thus very frequently assent to terms without +attaching to them any meaning, either because they think they once +understood them, or imagine they received them from others by whom +they were correctly understood. This, however, is not the place to +treat of this matter in detail, seeing the nature of the human body +has not yet been expounded, nor the existence even of body +established; enough, nevertheless, appears to have been said to +enable one to distinguish such of our conceptions as are clear and +distinct from those that are obscure and confused. + + + LXXV. Summary of what must be observed in order to philosophize +correctly. + +Wherefore if we would philosophize in earnest, and give ourselves to +the search after all the truths we are capable of knowing, we must, +in the first place, lay aside our prejudices; in other words, we +must take care scrupulously to withhold our assent from the opinions +we have formerly admitted, until upon new examination we discover +that they are true. We must, in the next place, make an orderly +review of the notions we have in our minds, and hold as true all and +only those which we will clearly and distinctly apprehend. In this +way we will observe, first of all, that we exist in so far as it is +our nature to think, and at the same time that there is a God upon +whom we depend; and after considering his attributes we will be able +to investigate the truth of all other things, since God is the cause +of them. Besides the notions we have of God and of our mind, we will +likewise find that we possess the knowledge of many propositions +which are eternally true, as, for example, that nothing cannot be +the cause of anything, etc. We will farther discover in our minds +the knowledge of a corporeal or extended nature that may be moved, +divided, etc., and also of certain sensations that affect us, as of +pain, colours, tastes, etc., although we do not yet know the cause +of our being so affected; and, comparing what we have now learne'd, +by examining those things in their order, with our former confused +knowledge of them, we will acquire the habit of forming clear and +distinct conceptions of all the objects we are capable of knowing. +In these few precepts seem to me to be comprised the most general +and important principles of human knowledge. + + + LXXVI. That we ought to prefer the Divine authority to our +perception; [Footnote: "reasonings."--FRENCH]. but that, apart from +things revealed, we ought to assent to nothing that we do not +clearly apprehend. + +Above all, we must impress on our memory the infallible rule, that +what God has revealed is incomparably more certain than anything +else; and that, we ought to submit our belief to the Divine +authority rather than to our own judgment, even although perhaps the +light of reason should, with the greatest clearness and evidence, +appear to suggest to us something contrary to what is revealed. But +in things regarding which there is no revelation, it is by no means +consistent with the character of a philosopher to accept as true +what he has not ascertained to be such, and to trust more to the +senses, in other words, to the inconsiderate judgments of childhood +than to the dictates of mature reason. + + + + +PART II. +OF THE PRINCIPLES OF MATERIAL THINGS. + + +I. The grounds on which the existence of material things may be +known with certainty. + +Although we are all sufficiently persuaded of the existence of +material things, yet, since this was before called in question by +us, and since we reckoned the persuasion of their existence as among +the prejudices of our childhood, it is now necessary for us to +investigate the grounds on which this truth may be known with +certainty. In the first place, then, it cannot be doubted that every +perception we have comes to us from some object different from our +mind; for it is not in our power to cause ourselves to experience +one perception rather than another, the perception being entirely +dependent on the object which affects our senses. It may, indeed, be +matter of inquiry whether that object be God, or something different +from God; but because we perceive, or rather, stimulated by sense, +clearly and distinctly apprehend, certain matter extended in length, +breadth, and thickness, the various parts of which have different +figures and motions, and give rise to the sensation we have of +colours, smells, pain, etc., God would, without question, deserve to +be regarded as a deceiver, if he directly and of himself presented +to our mind the idea of this extended matter, or merely caused it to +be presented to us by some object which possessed neither extension, +figure, nor motion. For we clearly conceive this matter as entirely +distinct from God, and from ourselves, or our mind; and appear even +clearly to discern that the idea of it is formed in us on occasion +of objects existing out of our minds, to which it is in every +respect similar. But since God cannot deceive us, for this is +repugnant to his nature, as has been already remarked, we must +unhesitatingly conclude that there exists a certain object extended +in length, breadth, and thickness, and possessing all those +properties which we clearly apprehend to belong to what is extended. +And this extended substance is what we call body or matter. + + + II. How we likewise know that the human body is closely connected +with the mind. + +We ought also to conclude that a certain body is more closely united +to our mind than any other, because we clearly observe that pain and +other sensations affect us without our foreseeing them; and these, +the mind is conscious, do not arise from itself alone, nor pertain +to it, in so far as it is a thing which thinks, but only in so far +as it is united to another thing extended and movable, which is +called the human body. But this is not the place to treat in detail +of this matter. + + + III. That the perceptions of the senses do not teach us what is in +reality in things, but what is beneficial of hurtful to the +composite whole of mind and body. + +It will be sufficient to remark that the perceptions of the senses +are merely to be referred to this intimate union of the human body +and mind, and that they usually make us aware of what, in external +objects, may be useful or adverse to this union, but do not present +to us these objects as they are in themselves, unless occasionally +and by accident. For, after this observation, we will without +difficulty lay aside the prejudices of the senses, and will have +recourse to our understanding alone on this question by reflecting +carefully on the ideas implanted in it by nature. + + + IV. That the nature of body consists not in weight hardness, colour +and the like, but in extension alone. + +In this way we will discern that the nature of matter or body, +considered in general, does not consist in its being hard, or +ponderous, or coloured, or that which affects our senses in any +other way, but simply in its being a substance extended in length, +breadth, and depth. For with respect to hardness, we know nothing of +it by sense farther than that the parts of hard bodies resist the +motion of our hands on coming into contact with them; but if every +time our hands moved towards any part, all the bodies in that place +receded as quickly as our hands approached, we should never feel +hardness; and yet we have no reason to believe that bodies which +might thus recede would on this account lose that which makes them +bodies. The nature of body does not, therefore, consist in hardness. +In the same way, it may be shown that weight, colour, and all the +other qualities of this sort, which are perceived in corporeal +matter, may be taken from it, itself meanwhile remaining entire: it +thus follows that the nature of body depends on none of these. + + + V. That the truth regarding the nature of body is obscured by the +opinions respecting rarefaction and a vacuum with which we are pre- +occupied. + +There still remain two causes to prevent its being fully admitted +that the true nature of body consists in extension alone. The first +is the prevalent opinion, that most bodies admit of being so +rarefied and condensed that, when rarefied, they have greater +extension than when condensed; and some even have subtilized to such +a degree as to make a distinction between the substance of body and +its quantity, and between quantity itself and extension. The second +cause is this, that where we conceive only extension in length, +breadth, and depth, we are not in the habit of saying that body is +there, but only space and further void space, which the generality +believe to be a mere negation. + + + VI. In what way rarefaction takes place. + +But with regard to rarefaction and condensation, whoever gives his +attention to his own thoughts, and admits nothing of which he is not +clearly conscious, will not suppose that there is anything in those +processes further than a change of figure in the body rarefied or +condensed: so that, in other words, rare bodies are those between +the parts of which there are numerous distances filled with other +bodies; and dense bodies, on the other hand, those whose parts +approaching each other, either diminish these distances or take them +wholly away, in the latter of which cases the body is rendered +absolutely dense. The body, however, when condensed, has not, +therefore, less extension than when the parts embrace a greater +space, owing to their removal from each other, and their dispersion +into branches. For we ought not to attribute to it the extension of +the pores or distances which its parts do not occupy when it is +rarefied, but to the other bodies that fill these interstices; just +as when we see a sponge full of water or any other liquid, we do not +suppose that each part of the sponge has on this account greater +extension than when compressed and dry, but only that its pores are +wider, and therefore that the body is diffused over a larger space. + + + VII. That rarefaction cannot be intelligibly explained unless in +the way here proposed. + +And indeed I am unable to discover the force of the reasons which +have induced some to say that rarefaction is the result of the +augmentation of the quantity of body, rather than to explain it on +the principle exemplified in the case of a sponge. For although when +air or water is rarefied we do not see any of the pores that are +rendered large, or the new body that is added to occupy them, it is +yet less agreeable to reason to suppose something that is +unintelligible for the purpose of giving a verbal and merely +apparent explanation of the rarefaction of bodies, than to conclude, +because of their rarefaction, that there are pores or distances +between the parts which are increased in size, and filled with some +new body. Nor ought we to refrain from assenting to this +explanation, because we perceive this new body by none of our +senses, for there is no reason which obliges us to believe that we +should perceive by our senses all the bodies in existence. And we +see that it is very easy to explain rarefaction in this manner, but +impossible in any other; for, in fine, there would be, as appears to +me, a manifest contradiction in supposing that any body was +increased by a quantity or extension which it had not before, +without the addition to it of a new extended substance, in other +words, of another body, because it is impossible to conceive any +addition of extension or quantity to a thing without supposing the +addition of a substance having quantity or extension, as will more +clearly appear from what follows. + + + VIII. That quantity and number differ only in thought (RATIONE) +from that which has quantity and is numbered. + +For quantity differs from extended substance, and number from what +is numbered, not in reality but merely in our thought; so that, for +example, we may consider the whole nature of a corporeal substance +which is comprised in a space of ten feet, although we do not attend +to this measure of ten feet, for the obvious reason that the thing +conceived is of the same nature in any part of that space as in the +whole; and, on the other hand, we can conceive the number ten, as +also a continuous quantity of ten feet, without thinking of this +determinate substance, because the concept of the number ten is +manifestly the same whether we consider a number of ten feet or ten +of anything else; and we can conceive a continuous quantity of ten +feet without thinking of this or that determinate substance, +although we cannot conceive it without some extended substance of +which it is the quantity. It is in reality, however, impossible that +any, even the least part, of such quantity or extension, can be +taken away, without the retrenchment at the same time of as much of +the substance, nor, on the other hand, can we lessen the substance, +without at the same time taking as much from the quantity or +extension. + + + IX. That corporeal substance, when distinguished from its quantity, +is confusedly conceived as something incorporeal. + +Although perhaps some express themselves otherwise on this matter, I +am nevertheless convinced that they do not think differently from +what I have now said: for when they distinguish (corporeal) +substance from extension or quantity, they either mean nothing by +the word (corporeal) substance, or they form in their minds merely a +confused idea of incorporeal substance, which they falsely attribute +to corporeal, and leave to extension the true idea of this corporeal +substance; which extension they call an accident, but with such +impropriety as to make it easy to discover that their words are not +in harmony with their thoughts. + + + X. What space or internal place is. + +Space or internal place, and the corporeal substance which is +comprised in it, are not different in reality, but merely in the +mode in which they are wont to be conceived by us. For, in truth, +the same extension in length, breadth, and depth, which constitutes +space, constitutes body; and the difference between them lies only +in this, that in body we consider extension as particular, and +conceive it to change with the body; whereas in space we attribute +to extension a generic unity, so that after taking from a certain +space the body which occupied it, we do not suppose that we have at +the same time removed the extension of the space, because it appears +to us that the same extension remains there so long as it is of the +same magnitude and figure, and preserves the same situation in +respect to certain bodies around it, by means of which we determine +this space. + + + XI. How space is not in reality different from corporeal substance. + +And indeed it will be easy to discern that it is the same extension +which constitutes the nature of body as of space, and that these two +things are mutually diverse only as the nature of the genus and +species differs from that of the individual, provided we reflect on +the idea we have of any body, taking a stone for example, and reject +all that is not essential to the nature of body. In the first place, +then, hardness may be rejected, because if the stone were liquefied +or reduced to powder, it would no longer possess hardness, and yet +would not cease to be a body; colour also may be thrown out of +account, because we have frequently seen stones so transparent as to +have no colour; again, we may reject weight, because we have the +case of fire, which, though very light, is still a body; and, +finally, we may reject cold, heat, and all the other qualities of +this sort, either because they are not considered as in the stone, +or because, with the change of these qualities, the stone is not +supposed to have lost the nature of body. After this examination we +will find that nothing remains in the idea of body, except that it +is something extended in length, breadth, and depth; and this +something is comprised in our idea of space, not only of that which +is full of body, but even of what is called void space. + + + XII. How space differs from body in our mode of conceiving it. + +There is, however, some difference between them in the mode of +conception; for if we remove a stone from the space or place in +which it was, we conceive that its extension also is taken away, +because we regard this as particular, and inseparable from the stone +itself: but meanwhile we suppose that the same extension of place in +which this stone was remains, although the place of the stone be +occupied by wood, water, air, or by any other body, or be even +supposed vacant, because we now consider extension in general, and +think that the same is common to stones, wood, water, air, and other +bodies, and even to a vacuum itself, if there is any such thing, +provided it be of the same magnitude and figure as before, and +preserve the same situation among the external bodies which +determine this space. + + + XIII. What external place is. + +The reason of which is, that the words place and space signify +nothing really different from body which is said to be in place, but +merely designate its magnitude, figure, and situation among other +bodies. For it is necessary, in order to determine this situation, +to regard certain other bodies which we consider as immovable; and, +according as we look to different bodies, we may see that the same +thing at the same time does and does not change place. For example, +when a vessel is being carried out to sea, a person sitting at the +stern may be said to remain always in one place, if we look to the +parts of the vessel, since with respect to these he preserves the +same situation; and on the other hand, if regard be had to the +neighbouring shores, the same person will seem to be perpetually +changing place, seeing he is constantly receding from one shore and +approaching another. And besides, if we suppose that the earth +moves, and that it makes precisely as much way from west to east as +the vessel from east to west, we will again say that the person at +the stern does not change his place, because this place will be +determined by certain immovable points which we imagine to be in the +heavens. But if at length we are persuaded that there are no points +really immovable in the universe, as will hereafter be shown to be +probable, we will thence conclude that nothing has a permanent place +unless in so far as it is fixed by our thought. + + + XIV. Wherein place and space differ. + +The terms place and space, however, differ in signification, because +place more expressly designates situation than magnitude or figure, +while, on the other hand, we think of the latter when we speak of +space. For we frequently say that a thing succeeds to the place of +another, although it be not exactly of the same magnitude or figure; +but we do not therefore admit that it occupies the same space as the +other; and when the situation is changed we say that the place also +is changed, although there are the same magnitude and figure as +before: so that when we say that a thing is in a particular place, +we mean merely that it is situated in a determinate way in respect +of certain other objects; and when we add that it occupies such a +space or place, we understand besides that it is of such determinate +magnitude and figure as exactly to fill this space. + + + XV. How external place is rightly taken for the superficies of the +surrounding body. + +And thus we never indeed distinguish space from extension in length, +breadth, and depth; we sometimes, however, consider place as in the +thing placed, and at other times as out of it. Internal place indeed +differs in no way from space; but external place may be taken for +the superficies that immediately surrounds the thing placed. It +ought to be remarked that by superficies we do not here understand +any part of the surrounding body, but only the boundary between the +surrounding and surrounded bodies, which is nothing more than a +mode; or at least that we speak of superficies in general which is +no part of one body rather than another, but is always considered +the same, provided it retain the same magnitude and figure. For +although the whole surrounding body with its superficies were +changed, it would not be supposed that the body which was surrounded +by it had therefore changed its place, if it meanwhile preserved the +same situation with respect to the other bodies that are regarded as +immovable. Thus, if we suppose that a boat is carried in one +direction by the current of a stream, and impelled by the wind in +the opposite with an equal force, so that its situation with respect +to the banks is not changed, we will readily admit that it remains +in the same place, although the whole superficies which surrounds it +is incessantly changing. + + + XVI. That a vacuum or space in which there is absolutely no body is +repugnant to reason. + +With regard to a vacuum, in the philosophical sense of the term, +that is, a space in which there is no substance, it is evident that +such does not exist, seeing the extension of space or internal place +is not different from that of body. For since from this alone, that +a body has extension in length, breadth, and depth, we have reason +to conclude that it is a substance, it being absolutely +contradictory that nothing should possess extension, we ought to +form a similar inference regarding the space which is supposed void, +viz., that since there is extension in it there is necessarily also +substance. + + + XVII. That a vacuum in the ordinary use of the term does not +exclude all body. + +And, in truth, by the term vacuum in its common use, we do not mean +a place or space in which there is absolutely nothing, but only a +place in which there is none of those things we presume ought to be +there. Thus, because a pitcher is made to hold water, it is said to +be empty when it is merely filled with air; or if there are no fish +in a fish-pond, we say there is nothing in it, although it be full +of water; thus a vessel is said to be empty, when, in place of the +merchandise which it was designed to carry, it is loaded with sand +only, to enable it to resist the violence of the wind; and, finally, +it is in the same sense that we say space is void when it contains +nothing sensible, although it contain created and self-subsisting +matter; for we are not in the habit of considering the bodies near +us, unless in so far as they cause in our organs of sense, +impressions strong enough to enable us to perceive them. And if, in +place of keeping in mind what ought to be understood by these terms +a vacuum and nothing, we afterwards suppose that in the space we +called a vacuum, there is not only no sensible object, but no object +at all, we will fall into the same error as if, because a pitcher in +which there is nothing but air, is, in common speech, said to be +empty, we were therefore to judge that the air contained in it is +not a substance (RES SUBSISTENS). + + + XVIII. How the prejudice of an absolute vacuum is to be corrected. + +We have almost all fallen into this error from the earliest age, +for, observing that there is no necessary connection between a +vessel and the body it contains, we thought that God at least could +take from a vessel the body which occupied it, without it being +necessary that any other should be put in the place of the one +removed. But that we may be able now to correct this false opinion, +it is necessary to remark that there is in truth no connection +between the vessel and the particular body which it contains, but +that there is an absolutely necessary connection between the concave +figure of the vessel and the extension considered generally which +must be comprised in this cavity; so that it is not more +contradictory to conceive a mountain without a valley than such a +cavity without the extension it contains, or this extension apart +from an extended substance, for, as we have often said, of nothing +there can be no extension. And accordingly, if it be asked what +would happen were God to remove from a vessel all the body contained +in it, without permitting another body to occupy its place, the +answer must be that the sides of the vessel would thus come into +proximity with each other. For two bodies must touch each other when +there is nothing between them, and it is manifestly contradictory +for two bodies to be apart, in other words, that there should be a +distance between them, and this distance yet be nothing; for all +distance is a mode of extension, and cannot therefore exist without +an extended substance. + + + XIX. That this confirms what was said of rarefaction. + +After we have thus remarked that the nature of corporeal substance +consists only in its being an extended thing, and that its extension +is not different from that which we attribute to space, however +empty, it is easy to discover the impossibility of any one of its +parts in any way whatsoever occupying more space at one time than at +another, and thus of being otherwise rarefied than in the way +explained above; and it is easy to perceive also that there cannot +be more matter or body in a vessel when it is filled with lead or +gold, or any other body however heavy and hard, than when it but +contains air and is supposed to be empty: for the quantity of the +parts of which a body is composed does not depend on their weight or +hardness, but only on the extension, which is always equal in the +same vase. + + + XX. That from this the non-existence of atoms may likewise be +demonstrated. + +We likewise discover that there cannot exist any atoms or parts of +matter that are of their own nature indivisible. For however small +we suppose these parts to be, yet because they are necessarily +extended, we are always able in thought to divide any one of them +into two or more smaller parts, and may accordingly admit their +divisibility. For there is nothing we can divide in thought which we +do not thereby recognize to be divisible; and, therefore, were we to +judge it indivisible our judgment would not be in harmony with the +knowledge we have of the thing; and although we should even suppose +that God had reduced any particle of matter to a smallness so +extreme that it did not admit of being further divided, it would +nevertheless be improperly styled indivisible, for though God had +rendered the particle so small that it was not in the power of any +creature to divide it, he could not however deprive himself of the +ability to do so, since it is absolutely impossible for him to +lessen his own omnipotence, as was before observed. Wherefore, +absolutely speaking, the smallest extended particle is always +divisible, since it is such of its very nature. + + + XXI. It is thus also demonstrated that the extension of the world +is indefinite. + +We further discover that this world or the whole (universitas) of +corporeal substance, is extended without limit, for wherever we fix +a limit, we still not only imagine beyond it spaces indefinitely +extended, but perceive these to be truly imaginable, in other words, +to be in reality such as we imagine them; so that they contain in +them corporeal substance indefinitely extended, for, as has been +already shown at length, the idea of extension which we conceive in +any space whatever is plainly identical with the idea of corporeal +substance. + + + XXII. It also follows that the matter of the heavens and earth is +the same, and that there cannot be a plurality of worlds. + +And it may also be easily inferred from all this that the earth and +heavens are made of the same matter; and that even although there +were an infinity of worlds, they would all be composed of this +matter; from which it follows that a plurality of worlds is +impossible, because we clearly conceive that the matter whose nature +consists only in its being an extended substance, already wholly +occupies all the imaginable spaces where these other worlds could +alone be, and we cannot find in ourselves the idea of any other +matter. + + + XXIII. That all the variety of matter, or the diversity of its +forms, depends on motion. + +There is therefore but one kind of matter in the whole universe, and +this we know only by its being extended. All the properties we +distinctly perceive to belong to it are reducible to its capacity of +being divided and moved according to its parts; and accordingly it +is capable of all those affections which we perceive can arise from +the motion of its parts. For the partition of matter in thought +makes no change in it; but all variation of it, or diversity of +form, depends on motion. The philosophers even seem universally to +have observed this, for they said that nature was the principle of +motion and rest, and by nature they understood that by which all +corporeal things become such as they are found in experience. + + + XXIV. What motion is, taking the term in its common use. + +But motion (viz., local, for I can conceive no other kind of motion, +and therefore I do not think we ought to suppose there is any other +in nature), in the ordinary sense of the term, is nothing more than +the action by which a body passes from one place to another. And +just as we have remarked above that the same thing may be said to +change and not to change place at the same time, so also we may say +that the same thing is at the same time moved and not moved. Thus, +for example, a person seated in a vessel which is setting sail, +thinks he is in motion if he look to the shore that he has left, and +consider it as fixed; but not if he regard the ship itself, among +the parts of which he preserves always the same situation. Moreover, +because we are accustomed to suppose that there is no motion without +action, and that in rest there is the cessation of action, the +person thus seated is more properly said to be at rest than in +motion, seeing he is not conscious of being in action. + + + XXV. What motion is properly so called. + +But if, instead of occupying ourselves with that which has no +foundation, unless in ordinary usage, we desire to know what ought +to be understood by motion according to the truth of the thing, we +may say, in order to give it a determinate nature, that it is THE +TRANSPORTING OF ONE PART OF MATTER OR OF ONE BODY FROM THE VICINITY +OF THOSE BODIES THAT ARE IN IMMEDIATE CONTACT WITH IT, OR WHICH WE +REGARD AS AT REST, to the vicinity of other bodies. By a body as a +part of matter, I understand all that which is transferred together, +although it be perhaps composed of several parts, which in +themselves have other motions; and I say that it is the transporting +and not the force or action which transports, with the view of +showing that motion is always in the movable thing, not in that +which moves; for it seems to me that we are not accustomed to +distinguish these two things with sufficient accuracy. Farther, I +understand that it is a mode of the movable thing, and not a +substance, just as figure is a property of the thing figured, and +repose of that which is at rest. + + + + +PART III. +OF THE VISIBLE WORLD. + + + I. That we cannot think too highly of the works of God. + +Having now ascertained certain principles of material things, which +were sought, not by the prejudices of the senses, but by the light +of reason, and which thus possess so great evidence that we cannot +doubt of their truth, it remains for us to consider whether from +these alone we can deduce the explication of all the phenomena of +nature. We will commence with those phenomena that are of the +greatest generality, and upon which the others depend, as, for +example, with the general structure of this whole visible world. But +in order to our philosophizing aright regarding this, two things are +first of all to be observed. The first is, that we should ever bear +in mind the infinity of the power and goodness of God, that we may +not fear falling into error by imagining his works to be too great, +beautiful, and perfect, but that we may, on the contrary, take care +lest, by supposing limits to them of which we have no certain +knowledge, we appear to think less highly than we ought of the power +of God. + + II. That we ought to beware lest, in our presumption, we imagine +that the ends which God proposed to himself in the creation of the +world are understood by us. + +The second is, that we should beware of presuming too highly of +ourselves, as it seems we should do if we supposed certain limits to +the world, without being assured of their existence either by +natural reasons or by divine revelation, as if the power of our +thought extended beyond what God has in reality made; but likewise +still more if we persuaded ourselves that all things were created by +God for us only, or if we merely supposed that we could comprehend +by the power of our intellect the ends which God proposed to himself +in creating the universe. + + III. In what sense it may be said that all things were created for +the sake of man. + +For although, as far as regards morals, it may be a pious thought to +believe that God made all things for us, seeing we may thus be +incited to greater gratitude and love toward him; and although it is +even in some sense true, because there is no created thing of which +we cannot make some use, if it be only that of exercising our mind +in considering it, and honouring God on account of it, it is yet by +no means probable that all things were created for us in this way +that God had no other end in their creation; and this supposition +would be plainly ridiculous and inept in physical reasoning, for we +do not doubt but that many things exist, or formerly existed and +have now ceased to be, which were never seen or known by man, and +were never of use to him. + + + + +PART IV. +OF THE EARTH. + + + CLXXXVIII. Of what is to be borrowed from disquisitions on animals +and man to advance the knowledge of material objects. + +I should add nothing farther to this the Fourth Part of the +Principles of Philosophy, did I purpose carrying out my original +design of writing a Fifth and Sixth Part, the one treating of things +possessed of life, that is, animals and plants, and the other of +man. But because I have not yet acquired sufficient knowledge of all +the matters of which I should desire to treat in these two last +parts, and do not know whether I shall ever have sufficient leisure +to finish them, I will here subjoin a few things regarding the +objects of our senses, that I may not, for the sake of the latter, +delay too long the publication of the former parts, or of what may +be desiderated in them, which I might have reserved for explanation +in those others: for I have hitherto described this earth, and +generally the whole visible world, as if it were merely a machine in +which there was nothing at all to consider except the figures and +motions of its parts, whereas our senses present to us many other +things, for example colours, smells, sounds, and the like, of which, +if I did not speak at all, it would be thought I had omitted the +explication of the majority of the objects that are in nature. + + + CLXXXIX. What perception (SENSUS) is, and how we perceive. + +We must know, therefore, that although the human soul is united to +the whole body, it has, nevertheless, its principal seat in the +brain, where alone it not only understands and imagines, but also +perceives; and this by the medium of the nerves, which are extended +like threads from the brain to all the other members, with which +they are so connected that we can hardly touch any one of them +without moving the extremities of some of the nerves spread over it; +and this motion passes to the other extremities of those nerves +which are collected in the brain round the seat of the soul, +[Footnote: *** FOOTNOTE NOT VISIBLE IN PAGE IMAGE (#98, Text p 195)] +as I have already explained with sufficient minuteness in the fourth +chapter of the Dioptrics. But the movements which are thus excited +in the brain by the nerves variously affect the soul or mind, which +is intimately conjoined with the brain, according to the diversity +of the motions themselves. And the diverse affections of the mind or +thoughts that immediately arise from these motions, are called +perceptions of the senses (SENSUUM PERCEPTIONES), or, as we commonly +speak, sensations (SENSUS). + + + CXC. Of the distinction of the senses; and, first, of the internal, +that is, of the affections of the mind (passions), and the natural +appetites. + +The varieties of these sensations depend, firstly, on the diversity +of the nerves themselves, and, secondly, of the movements that are +made in each nerve. We have not, however, as many different senses +as there are nerves. We can distinguish but seven principal classes +of nerves, of which two belong to the internal, and the other five +to the external senses. The nerves which extend to the stomach, the +oesophagus, the fauces, and the other internal parts that are +subservient to our natural wants, constitute one of our internal +senses. This is called the natural appetite (APPETITUS NATURALIS). +The other internal sense, which embraces all the emotions +(COMMOTIONES) of the mind or passions, and affections, as joy, +sadness, love, hate, and the like, depends upon the nerves which +extend to the heart and the parts about the heart, and are +exceedingly small; for, by way of example, when the blood happens to +be pure and well tempered, so that it dilates in the heart more +readily and strongly than usual, this so enlarges and moves the +small nerves scattered around the orifices, that there is thence a +corresponding movement in the brain, which affects the mind with a +certain natural feeling of joy; and as often as these same nerves +are moved in the same way, although this is by other causes, they +excite in our mind the same feeling (sensus, sentiment). Thus, the +imagination of the enjoyment of a good does not contain in itself +the feeling of joy, but it causes the animal spirits to pass from +the brain to the muscles in which these nerves are inserted; and +thus dilating the orifices of the heart, it also causes these small +nerves to move in the way appointed by nature to afford the +sensation of joy. Thus, when we receive news, the mind first of all +judges of it, and if the news be good, it rejoices with that +intellectual joy (GAUDIUM INTELLECTUALE) which is independent of any +emotion (COMMOTIO) of the body, and which the Stoics did not deny to +their wise man [although they supposed him exempt from all passion]. +But as soon as this joy passes from the understanding to the +imagination, the spirits flow from the brain to the muscles that are +about the heart, and there excite the motion of the small nerves, by +means of which another motion is caused in the brain, which affects +the mind with the sensation of animal joy (LAETITIA ANIMALIS). On +the same principle, when the blood is so thick that it flows but +sparingly into the ventricles of the heart, and is not there +sufficiently dilated, it excites in the same nerves a motion quite +different from the preceding, which, communicated to the brain, +gives to the mind the sensation of sadness, although the mind itself +is perhaps ignorant of the cause of its sadness. And all the other +causes which move these nerves in the same way may also give to the +mind the same sensation. But the other movements of the same nerves +produce other effects, as the feelings of love, hate, fear, anger, +etc., as far as they are merely affections or passions of the mind; +in other words, as far as they are confused thoughts which the mind +has not from itself alone, but from its being closely joined to the +body, from which it receives impressions; for there is the widest +difference between these passions and the distinct thoughts which we +have of what ought to be loved, or chosen, or shunned, etc., +[although these are often enough found together]. The natural +appetites, as hunger, thirst, and the others, are likewise +sensations excited in the mind by means of the nerves of the +stomach, fauces, and other parts, and are entirely different from +the will which we have to eat, drink, [and to do all that which we +think proper for the conservation of our body]; but, because this +will or appetition almost always accompanies them, they are +therefore named appetites. + + + CXCI. Of the external senses; and first of touch. + +We commonly reckon the external senses five in number, because there +are as many different kinds of objects which move the nerves and +their organs, and an equal number of kinds of confused thoughts +excited in the soul by these emotions. In the first place, the +nerves terminating in the skin of the whole body can be touched +through this medium by any terrene objects whatever, and moved by +these wholes, in one way by their hardness, in another by their +gravity, in a third by their heat, in a fourth by their humidity, +etc.--and in as many diverse modes as they are either moved or +hindered from their ordinary motion, to that extent are diverse +sensations excited in the mind, from which a corresponding number of +tactile qualities derive their appellations. Besides this, when +these nerves are moved a little more powerfully than usual, but not +nevertheless to the degree by which our body is in any way hurt, +there thus arises a sensation of titillation, which is naturally +agreeable to the mind, because it testifies to it of the powers of +the body with which it is joined, [in that the latter can suffer the +action causing this titillation, without being hurt]. But if this +action be strong enough to hurt our body in any way, this gives to +our mind the sensation of pain. And we thus see why corporeal +pleasure and pain, although sensations of quite an opposite +character, arise nevertheless from causes nearly alike. + + + CXCII. Of taste. + +In the second place, the other nerves scattered over the tongue and +the parts in its vicinity are diversely moved by the particles of +the same bodies, separated from each other and floating in the +saliva in the mouth, and thus cause sensations of diverse tastes +according to the diversity of figure in these particles. [Footnote: +In the French this section begins, "Taste, after touch the grossest +of the senses," etc.] + + + CXCIII. Of smell. + +Thirdly, two nerves also or appendages of the brain, for they do not +go beyond the limits of the skull, are moved by the particles of +terrestrial bodies, separated and flying in the air, not indeed by +all particles indifferently, but by those only that are sufficiently +subtle and penetrating to enter the pores of the bone we call the +spongy, when drawn into the nostrils, and thus to reach the nerves. +From the different motions of these particles arise the sensations +of the different smells. + + + CXCIV. Of hearing. + +Fourthly, there are two nerves within the ears, so attached to three +small bones that are mutually sustaining, and the first of which +rests on the small membrane that covers the cavity we call the +tympanum of the ear, that all the diverse vibrations which the +surrounding air communicates to this membrane are transmitted to the +mind by these nerves, and these vibrations give rise, according to +their diversity, to the sensations of the different sounds. + + + CXCV. Of sight. + +Finally, the extremities of the optic nerves, composing the coat in +the eyes called the retina, are not moved by the air nor by any +terrestrial object, but only by the globules of the second element, +whence we have the sense of light and colours: as I have already at +sufficient length explained in the Dioptrics and treatise of +Meteors. [Footnote: In the French this section begins, "Finally, +sight is the most subtle of all the senses," etc.] + + + CXCVI. That the soul perceives only in so far as it is in the +brain. + +It is clearly established, however, that the soul does not perceive +in so far as it is in each member of the body, but only in so far as +it is in the brain, where the nerves by their movements convey to it +the diverse actions of the external objects that touch the parts of +the body in which they are inserted. For, in the first place, there +are various maladies, which, though they affect the brain alone, yet +bring disorder upon, or deprive us altogether of the use of, our +senses, just as sleep, which affects the brain only, and yet takes +from us daily during a great part of our time the faculty of +perception, which afterwards in our waking state is restored to us. +The second proof is, that though there be no disease in the brain, +[or in the members in which the organs of the external senses are], +it is nevertheless sufficient to take away sensation from the part +of the body where the nerves terminate, if only the movement of one +of the nerves that extend from the brain to these members be +obstructed in any part of the distance that is between the two. And +the last proof is, that we sometimes feel pain as if in certain of +our members, the cause of which, however, is not in these members +where it is felt, but somewhere nearer the brain, through which the +nerves pass that give to the mind the sensation of it. I could +establish this fact by innumerable experiments; I will here, +however, merely refer to one of them. A girl suffering from a bad +ulcer in the hand, had her eyes bandaged whenever the surgeon came +to visit her, not being able to bear the sight of the dressing of +the sore; and, the gangrene having spread, after the expiry of a few +days the arm was amputated from the elbow [without the girl's +knowledge]; linen cloths tied one above the other were substituted +in place of the part amputated, so that she remained for some time +without knowing that the operation had been performed, and meanwhile +she complained of feeling various pains, sometimes in one finger of +the hand that was cut off, and sometimes in another. The only +explanation of this is, that the nerves which before stretched +downwards from the brain to the hand, and then terminated in the arm +close to the elbow, were there moved in the same way as they +required to be moved before in the hand for the purpose of +impressing on the mind residing in the brain the sensation of pain +in this or that finger. [And this clearly shows that the pain of the +hand is not felt by the mind in so far as it is in the hand, but in +so far as it is in the brain.] + + + CXCVII. That the nature of the mind is such that from the motion +alone of body the various sensations can be excited in it. + +In the next place, it can be proved that our mind is of such a +nature that the motions of the body alone are sufficient to excite +in it all sorts of thoughts, without it being necessary that these +should in any way resemble the motions which give rise to them, and +especially that these motions can excite in it those confused +thoughts called sensations (SENSUS, SENSATIONES). For we see that +words, whether uttered by the voice or merely written, excite in our +minds all kinds of thoughts and emotions. On the same paper, with +the same pen and ink, by merely moving the point of the pen over the +paper in a particular way, we can trace letters that will raise in +the minds of our readers the thoughts of combats, tempests, or the +furies, and the passions of indignation and sorrow; in place of +which, if the pen be moved in another way hardly different from the +former, this slight change will cause thoughts widely different from +the above, such as those of repose, peace, pleasantness, and the +quite opposite passions of love and joy. Some one will perhaps +object that writing and speech do not immediately excite in the mind +any passions, or imaginations of things different from the letters +and sounds, but afford simply the knowledge of these, on occasion of +which the mind, understanding the signification of the words, +afterwards excites in itself the imaginations and passions that +correspond to the words. But what will be said of the sensations of +pain and titillation? The motion merely of a sword cutting a part of +our skin causes pain, [but does not on that account make us aware of +the motion or figure of the sword]. And it is certain that this +sensation of pain is not less different from the motion that causes +it, or from that of the part of our body which the sword cuts, than +are the sensations we have of colour, sound, odour, or taste. On +this ground we may conclude that our mind is of such a nature that +the motions alone of certain bodies can also easily excite in it all +the other sensations, as the motion of a sword excites in it the +sensation of pain. + + + CXCVIII. That by our senses we know nothing of external objects +beyond their figure [or situation], magnitude, and motion. + +Besides, we observe no such difference between the nerves as to lead +us to judge that one set of them convey to the brain from the organs +of the external senses anything different from another, or that +anything at all reaches the brain besides the local motion of the +nerves themselves. And we see that local motion alone causes in us +not only the sensation of titillation and of pain, but also of light +and sounds. For if we receive a blow on the eye of sufficient force +to cause the vibration of the stroke to reach the retina, we see +numerous sparks of fire, which, nevertheless, are not out of our +eye; and when we stop our ear with our finger, we hear a humming +sound, the cause of which can only proceed from the agitation of the +air that is shut up within it. Finally, we frequently observe that +heat [hardness, weight], and the other sensible qualities, as far as +they are in objects, and also the forms of those bodies that are +purely material, as, for example, the forms of fire, are produced in +them by the motion of certain other bodies, and that these in their +turn likewise produce other motions in other bodies. And we can +easily conceive how the motion of one body may be caused by that of +another, and diversified by the size, figure, and situation of its +parts, but we are wholly unable to conceive how these same things +(viz., size, figure, and motion), can produce something else of a +nature entirely different from themselves, as, for example, those +substantial forms and real qualities which many philosophers suppose +to be in bodies; nor likewise can we conceive how these qualities or +forms possess force to cause motions in other bodies. But since we +know, from the nature of our soul, that the diverse motions of body +are sufficient to produce in it all the sensations which it has, and +since we learn from experience that several of its sensations are in +reality caused by such motions, while we do not discover that +anything besides these motions ever passes from the organs of the +external senses to the brain, we have reason to conclude that we in +no way likewise apprehend that in external objects, which we call +light, colour, smell, taste, sound, heat or cold, and the other +tactile qualities, or that which we call their substantial forms, +unless as the various dispositions of these objects which have the +power of moving our nerves in various ways. [Footnote: "the diverse +figures, situations, magnitudes, and motions of their parts."-- +French.] + + + CXCIX. That there is no phenomenon of nature whose explanation has +been omitted in this treatise. + +And thus it may be gathered, from an enumeration that is easily +made, that there is no phenomenon of nature whose explanation has +been omitted in this treatise; for beyond what is perceived by the +senses, there is nothing that can be considered a phenomenon of +nature. But leaving out of account motion, magnitude, figure, [and +the situation of the parts of each body], which I have explained as +they exist in body, we perceive nothing out of us by our senses +except light, colours, smells, tastes, sounds, and the tactile +qualities; and these I have recently shown to be nothing more, at +least so far as they are known to us, than certain dispositions of +the objects, consisting in magnitude, figure, and motion. + + + CC. That this treatise contains no principles which are not +universally received; and that this philosophy is not new, but of +all others the most ancient and common. + +But I am desirous also that it should be observed that, though I +have here endeavoured to give an explanation of the whole nature of +material things, I have nevertheless made use of no principle which +was not received and approved by Aristotle, and by the other +philosophers of all ages; so that this philosophy, so far from being +new, is of all others the most ancient and common: for I have in +truth merely considered the figure, motion, and magnitude of bodies, +and examined what must follow from their mutual concourse on the +principles of mechanics, which are confirmed by certain and daily +experience. But no one ever doubted that bodies are moved, and that +they are of various sizes and figures, according to the diversity of +which their motions also vary, and that from mutual collision those +somewhat greater than others are divided into many smaller, and thus +change figure. We have experience of the truth of this, not merely +by a single sense, but by several, as touch, sight, and hearing: we +also distinctly imagine and understand it. This cannot be said of +any of the other things that fall under our senses, as colours, +sounds, and the like; for each of these affects but one of our +senses, and merely impresses upon our imagination a confused image +of itself, affording our understanding no distinct knowledge of what +it is. + + + CCI. That sensible bodies are composed of insensible particles. + +But I allow many particles in each body that are perceived by none +of our senses, and this will not perhaps be approved of by those who +take the senses for the measure of the knowable. [We greatly wrong +human reason, however, as appears to me, if we suppose that it does +not go beyond the eye-sight]; for no one can doubt that there are +bodies so small as not to be perceptible by any of our senses, +provided he only consider what is each moment added to those bodies +that are being increased little by little, and what is taken from +those that are diminished in the same way. A tree increases daily, +and it is impossible to conceive how it becomes greater than it was +before, unless we at the same time conceive that some body is added +to it. But who ever observed by the senses those small bodies that +are in one day added to a tree while growing? Among the philosophers +at least, those who hold that quantity is indefinitely divisible, +ought to admit that in the division the parts may become so small as +to be wholly imperceptible. And indeed it ought not to be a matter +of surprise, that we are unable to perceive very minute bodies; for +the nerves that must be moved by objects to cause perception are not +themselves very minute, but are like small cords, being composed of +a quantity of smaller fibres, and thus the most minute bodies are +not capable of moving them. Nor do I think that any one who makes +use of his reason will deny that we philosophize with much greater +truth when we judge of what takes place in those small bodies which +are imperceptible from their minuteness only, after the analogy of +what we see occurring in those we do perceive, [and in this way +explain all that is in nature, as I have essayed to do in this +treatise], than when we give an explanation of the same things by +inventing I know not what novelties, that have no relation to the +things we actually perceive, [as first matter, substantial forms, +and all that grand array of qualities which many are in the habit of +supposing, each of which is more difficult to comprehend than all +that is professed to be explained by means of them]. + + + CCII. That the philosophy of Democritus is not less different from +ours than from the common. [Footnote: "that of Aristotle or the +others."--French.] + +But it may be said that Democritus also supposed certain corpuscles +that were of various figures, sizes, and motions, from the heaping +together and mutual concourse of which all sensible bodies arose; +and, nevertheless, his mode of philosophizing is commonly rejected +by all. To this I reply that the philosophy of Democritus was never +rejected by any one, because he allowed the existence of bodies +smaller than those we perceive, and attributed to them diverse +sizes, figures, and motions, for no one can doubt that there are in +reality such, as we have already shown; but it was rejected, in the +first place, because he supposed that these corpuscles were +indivisible, on which ground I also reject it; in the second place, +because he imagined there was a vacuum about them, which I show to +be impossible; thirdly, because he attributed gravity to these +bodies, of which I deny the existence in any body, in so far as a +body is considered by itself, because it is a quality that depends +on the relations of situation and motion which several bodies bear +to each other; and, finally, because he has not explained in +particular how all things arose from the concourse of corpuscles +alone, or, if he gave this explanation with regard to a few of them, +his whole reasoning was far from being coherent, [or such as would +warrant us in extending the same explanation to the whole of +nature]. This, at least, is the verdict we must give regarding his +philosophy, if we may judge of his opinions from what has been +handed down to us in writing. I leave it to others to determine +whether the philosophy I profess possesses a valid coherency, [and +whether on its principles we can make the requisite number of +deductions; and, inasmuch as the consideration of figure, magnitude, +and motion has been admitted by Aristotle and by all the others, as +well as by Democritus, and since I reject all that the latter has +supposed, with this single exception, while I reject generally all +that has been supposed by the others, it is plain that this mode of +philosophizing has no more affinity with that of Democritus than of +any other particular sect]. + + + CCIII. How we may arrive at the knowledge of the figures, +[magnitudes], and motions of the insensible particles of bodies. + +But, since I assign determinate figures, magnitudes, and motions to +the insensible particles of bodies, as if I had seen them, whereas I +admit that they do not fall under the senses, some one will perhaps +demand how I have come by my knowledge of them. [To this I reply, +that I first considered in general all the clear and distinct +notions of material things that are to be found in our +understanding, and that, finding no others except those of figures, +magnitudes, and motions, and of the rules according to which these +three things can be diversified by each other, which rules are the +principles of geometry and mechanics, I judged that all the +knowledge man can have of nature must of necessity be drawn from +this source; because all the other notions we have of sensible +things, as confused and obscure, can be of no avail in affording us +the knowledge of anything out of ourselves, but must serve rather to +impede it]. Thereupon, taking as my ground of inference the simplest +and best known of the principles that have been implanted in our +minds by nature, I considered the chief differences that could +possibly subsist between the magnitudes, and figures, and situations +of bodies insensible on account of their smallness alone, and what +sensible effects could be produced by their various modes of coming +into contact; and afterwards, when I found like effects in the +bodies that we perceive by our senses, I judged that they could have +been thus produced, especially since no other mode of explaining +them could be devised. And in this matter the example of several +bodies made by art was of great service to me: for I recognize no +difference between these and natural bodies beyond this, that the +effects of machines depend for the most part on the agency of +certain instruments, which, as they must bear some proportion to the +hands of those who make them, are always so large that their figures +and motions can be seen; in place of which, the effects of natural +bodies almost always depend upon certain organs so minute as to +escape our senses. And it is certain that all the rules of mechanics +belong also to physics, of which it is a part or species, [so that +all that is artificial is withal natural]: for it is not less +natural for a clock, made of the requisite number of wheels, to mark +the hours, than for a tree, which has sprung from this or that seed, +to produce the fruit peculiar to it. Accordingly, just as those who +are familiar with automata, when they are informed of the use of a +machine, and see some of its parts, easily infer from these the way +in which the others, that are not seen by them, are made; so from +considering the sensible effects and parts of natural bodies, I have +essayed to determine the character of their causes and insensible +parts. + + + CCIV. That, touching the things which our senses do not perceive, +it is sufficient to explain how they can be, [and that this is all +that Aristotle has essayed]. + +But here some one will perhaps reply, that although I have supposed +causes which could produce all natural objects, we ought not on this +account to conclude that they were produced by these causes; for, +just as the same artisan can make two clocks, which, though they +both equally well indicate the time, and are not different in +outward appearance, have nevertheless nothing resembling in the +composition of their wheels; so doubtless the Supreme Maker of +things has an infinity of diverse means at his disposal, by each of +which he could have made all the things of this world to appear as +we see them, without it being possible for the human mind to know +which of all these means he chose to employ. I most freely concede +this; and I believe that I have done all that was required, if the +causes I have assigned are such that their effects accurately +correspond to all the phenomena of nature, without determining +whether it is by these or by others that they are actually produced. +And it will be sufficient for the use of life to know the causes +thus imagined, for medicine, mechanics, and in general all the arts +to which the knowledge of physics is of service, have for their end +only those effects that are sensible, and that are accordingly to be +reckoned among the phenomena of nature. [Footnote: "have for their +end only to apply certain sensible bodies to each other in such a +way that, in the course of natural causes, certain sensible effects +may be produced; and we will be able to accomplish this quite as +well by considering the series of certain causes thus imagined, +although false, as if they were the true, since this series is +supposed similar as far as regards sensible effects."-French.] + +And lest it should be supposed that Aristotle did, or professed to +do, anything more than this, it ought to be remembered that he +himself expressly says, at the commencement of the seventh chapter +of the first book of the Meteorologies, that, with regard to things +which are not manifest to the senses, he thinks to adduce sufficient +reasons and demonstrations of them, if he only shows that they may +be such as he explains them. [Footnote: words in Greek] + + + CCV. That nevertheless there is a moral certainty that all the +things of this world are such as has been here shown they may be. + +But nevertheless, that I may not wrong the truth by supposing it +less certain than it is, I will here distinguish two kinds of +certitude. The first is called moral, that is, a certainty +sufficient for the conduct of life, though, if we look to the +absolute power of God, what is morally certain may be false. [Thus, +those who never visited Rome do not doubt that it is a city of +Italy, though it might be that all from whom they got their +information were deceived]. Again, if any one, wishing to decipher a +letter written in Latin characters that are not placed in regular +order, bethinks himself of reading a B wherever an A is found, and a +C wherever there is a B, and thus of substituting in place of each +letter the one which follows it in the order of the alphabet, and if +by this means he finds that there are certain Latin words composed +of these, he will not doubt that the true meaning of the writing is +contained in these words, although he may discover this only by +conjecture, and although it is possible that the writer of it did +not arrange the letters on this principle of alphabetical order, but +on some other, and thus concealed another meaning in it: for this is +so improbable [especially when the cipher contains a number of +words] as to seem incredible. But they who observe how many things +regarding the magnet, fire, and the fabric of the whole world, are +here deduced from a very small number of principles, though they +deemed that I had taken them up at random and without grounds, will +yet perhaps acknowledge that it could hardly happen that so many +things should cohere if these principles were false. + + + CCVI. That we possess even more than a moral certainty of it. + +Besides, there are some, even among natural, things which we judge +to be absolutely certain. [Absolute certainty arises when we judge +that it is impossible a thing can be otherwise than as we think it]. +This certainty is founded on the metaphysical ground, that, as God +is supremely good and the source of all truth, the faculty of +distinguishing truth from error which he gave us, cannot be +fallacious so long as we use it aright, and distinctly perceive +anything by it. Of this character are the demonstrations of +mathematics, the knowledge that material things exist, and the clear +reasonings that are formed regarding them. The results I have given +in this treatise will perhaps be admitted to a place in the class of +truths that are absolutely certain, if it be considered that they +are deduced in a continuous series from the first and most +elementary principles of human knowledge; especially if it be +sufficiently understood that we can perceive no external objects +unless some local motion be caused by them in our nerves, and that +such motion cannot be caused by the fixed stars, owing to their +great distance from us, unless a motion be also produced in them and +in the whole heavens lying between them and us: for these points +being admitted, all the others, at least the more general doctrines +which I have advanced regarding the world or earth [e. g., the +fluidity of the heavens, Part III., Section XLVI.], will appear to +be almost the only possible explanations of the phenomena they +present. + + + CCVII. That, however, I submit all my opinions to the authority of +the church. + +Nevertheless, lest I should presume too far, I affirm nothing, but +submit all these my opinions to the authority of the church and the +judgment of the more sage; and I desire no one to believe anything I +may have said, unless he is constrained to admit it by the force and +evidence of reason. + + +*** END OF THE PROJECT GUTENBERG EBOOK 4391 *** diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. 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D. +LATE PROFESSOR OF LOGIC AND RHETORIC IN THE UNIVERSITY OF GLASGOW + + + + +From the Publisher's Preface. + +The present volume contains a reprint of the preface and the first +part of the Principles of Philosophy, together with selections from +the second, third and fourth parts of that work, corresponding to +the extracts in the French edition of Gamier, are also given, as +well as an appendix containing part of Descartes' reply to the +Second Objections (viz., his formal demonstrations of the existence +of Deity). The translation is based on the original Latin edition of +the Principles, published in 1644. + +The work had been translated into French during Descartes' lifetime, +and personally revised and corrected by him, the French text is +evidently deserving of the same consideration as the Latin +originals, and consequently, the additions and variations of the +French version have also been given--the additions being put in +square brackets in the text and the variations in the footnotes. + +A copy of the title-page of the original edition, as given in Dr. C. +Guttler's work (Munich: C. H. Beck. 1901), are also reproduced in +the present volume. + + + + + + +SELECTIONS FROM THE PRINCIPLES OF PHILOSOPHY + +OF DESCARTES + +TRANSLATED FROM THE LATIN AND COLLATED WITH THE FRENCH + + + +LETTER OF THE AUTHOR + +TO THE FRENCH TRANSLATOR OF THE PRINCIPLES OF PHILOSOPHY SERVING FOR +A PREFACE. + +Sir,--The version of my principles which you have been at pains to +make, is so elegant and finished as to lead me to expect that the +work will be more generally read in French than in Latin, and better +understood. The only apprehension I entertain is lest the title +should deter some who have not been brought up to letters, or with +whom philosophy is in bad repute, because the kind they were taught +has proved unsatisfactory; and this makes me think that it will be +useful to add a preface to it for the purpose of showing what the +MATTER of the work is, what END I had in view in writing it, and +what UTILITY may be derived from it. But although it might be my +part to write a preface of this nature, seeing I ought to know those +particulars better than any other person, I cannot nevertheless +prevail upon myself to do anything more than merely to give a +summary of the chief points that fall, as I think, to be discussed +in it: and I leave it to your discretion to present to the public +such part of them as you shall judge proper. + +I should have desired, in the first place, to explain in it what +philosophy is, by commencing with the most common matters, as, for +example, that the word PHILOSOPHY signifies the study of wisdom, and +that by wisdom is to be understood not merely prudence in the +management of affairs, but a perfect knowledge of all that man can +know, as well for the conduct of his life as for the preservation of +his health and the discovery of all the arts, and that knowledge to +subserve these ends must necessarily be deduced from first causes; +so that in order to study the acquisition of it (which is properly +called philosophizing), we must commence with the investigation of +those first causes which are called PRINCIPLES. Now these principles +must possess TWO CONDITIONS: in the first place, they must be so +clear and evident that the human mind, when it attentively considers +them, cannot doubt of their truth; in the second place, the +knowledge of other things must be so dependent on them as that +though the principles themselves may indeed be known apart from what +depends on them, the latter cannot nevertheless be known apart from +the former. It will accordingly be necessary thereafter to endeavour +so to deduce from those principles the knowledge of the things that +depend on them, as that there may be nothing in the whole series of +deductions which is not perfectly manifest. God is in truth the only +being who is absolutely wise, that is, who possesses a perfect +knowledge of all things; but we may say that men are more or less +wise as their knowledge of the most important truths is greater or +less. And I am confident that there is nothing, in what I have now +said, in which all the learned do not concur. + +I should, in the next place, have proposed to consider the utility +of philosophy, and at the same time have shown that, since it +embraces all that the human mind can know, we ought to believe that +it is by it we are distinguished from savages and barbarians, and +that the civilisation and culture of a nation is regulated by the +degree in which true philosophy nourishes in it, and, accordingly, +that to contain true philosophers is the highest privilege a state +can enjoy. Besides this, I should have shown that, as regards +individuals, it is not only useful for each man to have intercourse +with those who apply themselves to this study, but that it is +incomparably better he should himself direct his attention to it; +just as it is doubtless to be preferred that a man should make use +of his own eyes to direct his steps, and enjoy by means of the same +the beauties of colour and light, than that he should blindly follow +the guidance of another; though the latter course is certainly +better than to have the eyes closed with no guide except one's self. +But to live without philosophizing is in truth the same as keeping +the eyes closed without attempting to open them; and the pleasure of +seeing all that sight discloses is not to be compared with the +satisfaction afforded by the discoveries of philosophy. And, +finally, this study is more imperatively requisite for the +regulation of our manners, and for conducting us through life, than +is the use of our eyes for directing our steps. The brutes, which +have only their bodies to conserve, are continually occupied in +seeking sources of nourishment; but men, of whom the chief part is +the mind, ought to make the search after wisdom their principal +care, for wisdom is the true nourishment of the mind; and I feel +assured, moreover, that there are very many who would not fail in +the search, if they would but hope for success in it, and knew the +degree of their capabilities for it. There is no mind, how ignoble +soever it be, which remains so firmly bound up in the objects of the +senses, as not sometime or other to turn itself away from them in +the aspiration after some higher good, although not knowing +frequently wherein that good consists. The greatest favourites of +fortune--those who have health, honours, and riches in abundance-- +are not more exempt from aspirations of this nature than others; +nay, I am persuaded that these are the persons who sigh the most +deeply after another good greater and more perfect still than any +they already possess. But the supreme good, considered by natural +reason without the light of faith, is nothing more than the +knowledge of truth through its first causes, in other words, the +wisdom of which philosophy is the study. And, as all these +particulars are indisputably true, all that is required to gain +assent to their truth is that they be well stated. + +But as one is restrained from assenting to these doctrines by +experience, which shows that they who make pretensions to philosophy +are often less wise and reasonable than others who never applied +themselves to the study, I should have here shortly explained +wherein consists all the science we now possess, and what are the +degrees of wisdom at which we have arrived. The first degree +contains only notions so clear of themselves that they can be +acquired without meditation; the second comprehends all that the +experience of the senses dictates; the third, that which the +conversation of other men teaches us; to which may be added as the +fourth, the reading, not of all books, but especially of such as +have been written by persons capable of conveying proper +instruction, for it is a species of conversation we hold with their +authors. And it seems to me that all the wisdom we in ordinary +possess is acquired only in these four ways; for I do not class +divine revelation among them, because it does not conduct us by +degrees, but elevates us at once to an infallible faith. + +There have been, indeed, in all ages great minds who endeavoured to +find a fifth road to wisdom, incomparably more sure and elevated +than the other four. The path they essayed was the search of first +causes and true principles, from which might be deduced the reasons +of all that can be known by man; and it is to them the appellation +of philosophers has been more especially accorded. I am not aware +that there is any one of them up to the present who has succeeded in +this enterprise. The first and chief whose writings we possess are +Plato and Aristotle, between whom there was no difference, except +that the former, following in the footsteps of his master, Socrates, +ingenuously confessed that he had never yet been able to find +anything certain, and that he was contented to write what seemed to +him probable, imagining, for this end, certain principles by which +he endeavoured to account for the other things. Aristotle, on the +other hand, characterised by less candour, although for twenty years +the disciple of Plato, and with no principles beyond those of his +master, completely reversed his mode of putting them, and proposed +as true and certain what it is probable he himself never esteemed as +such. But these two men had acquired much judgment and wisdom by the +four preceding means, qualities which raised their authority very +high, so much so that those who succeeded them were willing rather +to acquiesce in their opinions, than to seek better for themselves. +The chief question among their disciples, however, was as to whether +we ought to doubt of all things or hold some as certain,--a dispute +which led them on both sides into extravagant errors; for a part of +those who were for doubt, extended it even to the actions of life, +to the neglect of the most ordinary rules required for its conduct; +those, on the other hand, who maintained the doctrine of certainty, +supposing that it must depend upon the senses, trusted entirely to +them. To such an extent was this carried by Epicurus, that it is +said he ventured to affirm, contrary to all the reasonings of the +astronomers, that the sun is no larger than it appears. + +It is a fault we may remark in most disputes, that, as truth is the +mean between the two opinions that are upheld, each disputant +departs from it in proportion to the degree in which he possesses +the spirit of contradiction. But the error of those who leant too +much to the side of doubt, was not followed for any length of time, +and that of the opposite party has been to some extent corrected by +the doctrine that the senses are deceitful in many instances. +Nevertheless, I do not know that this error was wholly removed by +showing that certitude is not in the senses, but in the +understanding alone when it has clear perceptions; and that while we +only possess the knowledge which is acquired in the first four +grades of wisdom, we ought not to doubt of the things that appear to +be true in what regards the conduct of life, nor esteem them as so +certain that we cannot change our opinions regarding them, even +though constrained by the evidence of reason. + +From ignorance of this truth, or, if there was any one to whom it +was known, from neglect of it, the majority of those who in these +later ages aspired to be philosophers, blindly followed Aristotle, +so that they frequently corrupted the sense of his writings, and +attributed to him various opinions which he would not recognise as +his own were he now to return to the world; and those who did not +follow him, among whom are to be found many of the greatest minds, +did yet not escape being imbued with his opinions in their youth, as +these form the staple of instruction in the schools; and thus their +minds were so preoccupied that they could not rise to the knowledge +of true principles. And though I hold all the philosophers in +esteem, and am unwilling to incur odium by my censure, I can adduce +a proof of my assertion, which I do not think any of them will +gainsay, which is, that they all laid down as a principle what they +did not perfectly know. For example, I know none of them who did not +suppose that there was gravity in terrestrial bodies; but although +experience shows us very clearly that bodies we call heavy descend +towards the center of the earth, we do not, therefore, know the +nature of gravity, that is, the cause or principle in virtue of +which bodies descend, and we must derive our knowledge of it from +some other source. The same may be said of a vacuum and atoms, of +heat and cold, of dryness and humidity, and of salt, sulphur, and +mercury, and the other things of this sort which some have adopted +as their principles. But no conclusion deduced from a principle +which is not clear can be evident, even although the deduction be +formally valid; and hence it follows that no reasonings based on +such principles could lead them to the certain knowledge of any one +thing, nor consequently advance them one step in the search after +wisdom. And if they did discover any truth, this was due to one or +other of the four means above mentioned. Notwithstanding this, I am +in no degree desirous to lessen the honour which each of them can +justly claim; I am only constrained to say, for the consolation of +those who have not given their attention to study, that just as in +travelling, when we turn our back upon the place to which we were +going, we recede the farther from it in proportion as we proceed in +the new direction for a greater length of time and with greater +speed, so that, though we may be afterwards brought back to the +right way, we cannot nevertheless arrive at the destined place as +soon as if we had not moved backwards at all; so in philosophy, when +we make use of false principles, we depart the farther from the +knowledge of truth and wisdom exactly in proportion to the care with +which we cultivate them, and apply ourselves to the deduction of +diverse consequences from them, thinking that we are philosophizing +well, while we are only departing the farther from the truth; from +which it must be inferred that they who have learned the least of +all that has been hitherto distinguished by the name of philosophy +are the most fitted for the apprehension of truth. + +After making those matters clear, I should, in the next place, have +desired to set forth the grounds for holding that the true +principles by which we may reach that highest degree of wisdom +wherein consists the sovereign good of human life, are those I have +proposed in this work; and two considerations alone are sufficient +to establish this--the first of which is, that these principles are +very clear, and the second, that we can deduce all other truths from +them; for it is only these two conditions that are required in true +principles. But I easily prove that they are very clear; firstly, by +a reference to the manner in which I found them, namely, by +rejecting all propositions that were in the least doubtful, for it +is certain that such as could not be rejected by this test when they +were attentively considered, are the most evident and clear which +the human mind can know. Thus by considering that he who strives to +doubt of all is unable nevertheless to doubt that he is while he +doubts, and that what reasons thus, in not being able to doubt of +itself and doubting nevertheless of everything else, is not that +which we call our body, but what we name our mind or thought, I have +taken the existence of this thought for the first principle, from +which I very clearly deduced the following truths, namely, that +there is a God who is the author of all that is in the world, and +who, being the source of all truth, cannot have created our +understanding of such a nature as to be deceived in the judgments it +forms of the things of which it possesses a very clear and distinct +perception. Those are all the principles of which I avail myself +touching immaterial or metaphysical objects, from which I most +clearly deduce these other principles of physical or corporeal +things, namely, that there are bodies extended in length, breadth, +and depth, which are of diverse figures and are moved in a variety +of ways. Such are in sum the principles from which I deduce all +other truths. The second circumstance that proves the clearness of +these principles is, that they have been known in all ages, and even +received as true and indubitable by all men, with the exception only +of the existence of God, which has been doubted by some, because +they attributed too much to the perceptions of the senses, and God +can neither be seen nor touched. + +But, though all the truths which I class among my principles were +known at all times, and by all men, nevertheless, there has been no +one up to the present, who, so far as I know, has adopted them as +principles of philosophy: in other words, as such that we can deduce +from them the knowledge of whatever else is in the world. It +accordingly now remains for me to prove that they are such; and it +appears to me that I cannot better establish this than by the test +of experience: in other words, by inviting readers to peruse the +following work. For, though I have not treated in it of all matters- +-that being impossible--I think I have so explained all of which I +had occasion to treat, that they who read it attentively will have +ground for the persuasion that it is unnecessary to seek for any +other principles than those I have given, in order to arrive at the +most exalted knowledge of which the mind of man is capable; +especially if, after the perusal of my writings, they take the +trouble to consider how many diverse questions are therein discussed +and explained, and, referring to the writings of others, they see +how little probability there is in the reasons that are adduced in +explanation of the same questions by principles different from mine. +And that they may the more easily undertake this, I might have said +that those imbued with my doctrines have much less difficulty in +comprehending the writings of others, and estimating their true +value, than those who have not been so imbued; and this is precisely +the opposite of what I before said of such as commenced with the +ancient philosophy, namely, that the more they have studied it the +less fit are they for rightly apprehending the truth. + +I should also have added a word of advice regarding the manner of +reading this work, which is, that I should wish the reader at first +to go over the whole of it, as he would a romance, without greatly +straining his attention, or tarrying at the difficulties he may +perhaps meet with in it, with the view simply of knowing in general +the matters of which I treat; and that afterwards, if they seem to +him to merit a more careful examination, and he feel a desire to +know their causes, he may read it a second time, in order to observe +the connection of my reasonings; but that he must not then give it +up in despair, although he may not everywhere sufficiently discover +the connection of the proof, or understand all the reasonings--it +being only necessary to mark with a pen the places where the +difficulties occur, and continue to read without interruption to the +end; then, if he does not grudge to take up the book a third time, I +am confident he will find in a fresh perusal the solution of most of +the difficulties he will have marked before; and that, if any still +remain, their solution will in the end be found in another reading. + +I have observed, on examining the natural constitutions of different +minds, that there are hardly any so dull or slow of understanding as +to be incapable of apprehending good opinions, or even of acquiring +all the highest sciences, if they be but conducted along the right +road. And this can also be proved by reason; for, as the principles +are clear, and as nothing ought to be deduced from them, unless most +manifest inferences, no one is so devoid of intelligence as to be +unable to comprehend the conclusions that flow from them. But, +besides the entanglement of prejudices, from which no one is +entirely exempt, although it is they who have been the most ardent +students of the false sciences that receive the greatest detriment +from them, it happens very generally that people of ordinary +capacity neglect to study from a conviction that they want ability, +and that others, who are more ardent, press on too rapidly: whence +it comes to pass that they frequently admit principles far from +evident, and draw doubtful inferences from them. For this reason, I +should wish to assure those who are too distrustful of their own +ability that there is nothing in my writings which they may not +entirely understand, if they only take the trouble to examine them; +and I should wish, at the same time, to warn those of an opposite +tendency that even the most superior minds will have need of much +time and attention to remark all I designed to embrace therein. + +After this, that I might lead men to understand the real design I +had in publishing them, I should have wished here to explain the +order which it seems to me one ought to follow with the view of +instructing himself. In the first place, a man who has merely the +vulgar and imperfect knowledge which can be acquired by the four +means above explained, ought, before all else, to endeavour to form +for himself a code of morals, sufficient to regulate the actions of +his life, as well for the reason that this does not admit of delay +as because it ought to be our first care to live well. In the next +place, he ought to study Logic, not that of the schools, for it is +only, properly speaking, a dialectic which teaches the mode of +expounding to others what we already know, or even of speaking much, +without judgment, of what we do not know, by which means it corrupts +rather than increases good sense--but the logic which teaches the +right conduct of the reason with the view of discovering the truths +of which we are ignorant; and, because it greatly depends on usage, +it is desirable he should exercise himself for a length of time in +practising its rules on easy and simple questions, as those of the +mathematics. Then, when he has acquired some skill in discovering +the truth in these questions, he should commence to apply himself in +earnest to true philosophy, of which the first part is Metaphysics, +containing the principles of knowledge, among which is the +explication of the principal attributes of God, of the immateriality +of the soul, and of all the clear and simple notions that are in us; +the second is Physics, in which, after finding the true principles +of material things, we examine, in general, how the whole universe +has been framed; in the next place, we consider, in particular, the +nature of the earth, and of all the bodies that are most generally +found upon it, as air, water, fire, the loadstone and other +minerals. In the next place it is necessary also to examine singly +the nature of plants, of animals, and above all of man, in order +that we may thereafter be able to discover the other sciences that +are useful to us. Thus, all Philosophy is like a tree, of which +Metaphysics is the root, Physics the trunk, and all the other +sciences the branches that grow out of this trunk, which are reduced +to three principal, namely, Medicine, Mechanics, and Ethics. By the +science of Morals, I understand the highest and most perfect which, +presupposing an entire knowledge of the other sciences, is the last +degree of wisdom. + +But as it is not from the roots or the trunks of trees that we +gather the fruit, but only from the extremities of their branches, +so the principal utility of philosophy depends on the separate uses +of its parts, which we can only learn last of all. But, though I am +ignorant of almost all these, the zeal I have always felt in +endeavouring to be of service to the public, was the reason why I +published, some ten or twelve years ago, certain Essays on the +doctrines I thought I had acquired. The first part of these Essays +was a "Discourse on the Method of rightly conducting the Reason, and +seeking Truth in the Sciences," in which I gave a summary of the +principal rules of logic, and also of an imperfect ethic, which a +person may follow provisionally so long as he does not know any +better. The other parts were three treatises: the first of +Dioptrics, the second of Meteors, and the third of Geometry. In the +Dioptrics, I designed to show that we might proceed far enough in +philosophy as to arrive, by its means, at the knowledge of the arts +that are useful to life, because the invention of the telescope, of +which I there gave an explanation, is one of the most difficult that +has ever been made. In the treatise of Meteors, I desired to exhibit +the difference that subsists between the philosophy I cultivate and +that taught in the schools, in which the same matters are usually +discussed. In fine, in the Geometry, I professed to demonstrate that +I had discovered many things that were before unknown, and thus +afford ground for believing that we may still discover many others, +with the view of thus stimulating all to the investigation of truth. +Since that period, anticipating the difficulty which many would +experience in apprehending the foundations of the Metaphysics, I +endeavoured to explain the chief points of them in a book of +Meditations, which is not in itself large, but the size of which has +been increased, and the matter greatly illustrated, by the +Objections which several very learned persons sent to me on occasion +of it, and by the Replies which I made to them. At length, after it +appeared to me that those preceding treatises had sufficiently +prepared the minds of my readers for the Principles of Philosophy, I +also published it; and I have divided this work into four parts, the +first of which contains the principles of human knowledge, and which +may be called the First Philosophy, or Metaphysics. That this part, +accordingly, may be properly understood, it will be necessary to +read beforehand the book of Meditations I wrote on the same subject. +The other three parts contain all that is most general in Physics, +namely, the explication of the first laws or principles of nature, +and the way in which the heavens, the fixed stars, the planets, +comets, and generally the whole universe, were composed; in the next +place, the explication, in particular, of the nature of this earth, +the air, water, fire, the magnet, which are the bodies we most +commonly find everywhere around it, and of all the qualities we +observe in these bodies, as light, heat, gravity, and the like. In +this way, it seems to me, I have commenced the orderly explanation +of the whole of philosophy, without omitting any of the matters that +ought to precede the last which I discussed. But to bring this +undertaking to its conclusion, I ought hereafter to explain, in the +same manner, the nature of the other more particular bodies that are +on the earth, namely, minerals, plants, animals, and especially man; +finally, to treat thereafter with accuracy of Medicine, Ethics, and +Mechanics. I should require to do this in order to give to the world +a complete body of philosophy; and I do not yet feel myself so old,- +-I do not so much distrust my strength, nor do I find myself so far +removed from the knowledge of what remains, as that I should not +dare to undertake to complete this design, provided I were in a +position to make all the experiments which I should require for the +basis and verification of my reasonings. But seeing that would +demand a great expenditure, to which the resources of a private +individual like myself would not be adequate, unless aided by the +public, and as I have no ground to expect this aid, I believe that I +ought for the future to content myself with studying for my own +instruction, and posterity will excuse me if I fail hereafter to +labour for them. + +Meanwhile, that it may be seen wherein I think I have already +promoted the general good, I will here mention the fruits that may +be gathered from my Principles. The first is the satisfaction which +the mind will experience on finding in the work many truths before +unknown; for although frequently truth does not so greatly affect +our imagination as falsity and fiction, because it seems less +wonderful and is more simple, yet the gratification it affords is +always more durable and solid. The second fruit is, that in studying +these principles we will become accustomed by degrees to judge +better of all the things we come in contact with, and thus be made +wiser, in which respect the effect will be quite the opposite of the +common philosophy, for we may easily remark in those we call pedants +that it renders them less capable of rightly exercising their reason +than they would have been if they had never known it. The third is, +that the truths which they contain, being highly clear and certain, +will take away all ground of dispute, and thus dispose men's minds +to gentleness and concord; whereas the contrary is the effect of the +controversies of the schools, which, as they insensibly render those +who are exercised in them more wrangling and opinionative, are +perhaps the prime cause of the heresies and dissensions that now +harass the world. The last and chief fruit of these Principles is, +that one will be able, by cultivating them, to discover many truths +I myself have not unfolded, and thus passing by degrees from one to +another, to acquire in course of time a perfect knowledge of the +whole of philosophy, and to rise to the highest degree of wisdom. +For just as all the arts, though in their beginnings they are rude +and imperfect, are yet gradually perfected by practice, from their +containing at first something true, and whose effect experience +evinces; so in philosophy, when we have true principles, we cannot +fail by following them to meet sometimes with other truths; and we +could not better prove the falsity of those of Aristotle, than by +saying that men made no progress in knowledge by their means during +the many ages they prosecuted them. + +I well know that there are some men so precipitate and accustomed to +use so little circumspection in what they do, that, even with the +most solid foundations, they could not rear a firm superstructure; +and as it is usually those who are the readiest to make books, they +would in a short time mar all that I have done, and introduce +uncertainty and doubt into my manner of philosophizing, from which I +have carefully endeavoured to banish them, if people were to receive +their writings as mine, or as representing my opinions. I had, not +long ago, some experience of this in one of those who were believed +desirous of following me the most closely, [Footnote: Regius; see La +Vie de M. Descartes, reduite en abrege (Baillet). Liv. vii., chap. +vii.--T.] and one too of whom I had somewhere said that I had such +confidence in his genius as to believe that he adhered to no +opinions which I should not be ready to avow as mine; for he last +year published a book entitled "Fundamental Physics," in which, +although he seems to have written nothing on the subject of Physics +and Medicine which he did not take from my writings, as well from +those I have published as from another still imperfect on the nature +of animals, which fell into his hands; nevertheless, because he has +copied them badly, and changed the order, and denied certain +metaphysical truths upon which all Physics ought to be based, I am +obliged wholly to disavow his work, and here to request readers not +to attribute to me any opinion unless they find it expressly stated +in my own writings, and to receive no opinion as true, whether in my +writings or elsewhere, unless they see that it is very clearly +deduced from true principles. I well know, likewise, that many ages +may elapse ere all the truths deducible from these principles are +evolved out of them, as well because the greater number of such as +remain to be discovered depend on certain particular experiments +that never occur by chance, but which require to be investigated +with care and expense by men of the highest intelligence, as because +it will hardly happen that the same persons who have the sagacity to +make a right use of them, will possess also the means of making +them, and also because the majority of the best minds have formed so +low an estimate of philosophy in general, from the imperfections +they have remarked in the kind in vogue up to the present time, that +they cannot apply themselves to the search after truth. + +But, in conclusion, if the difference discernible between the +principles in question and those of every other system, and the +great array of truths deducible from them, lead them to discern the +importance of continuing the search after these truths, and to +observe the degree of wisdom, the perfection and felicity of life, +to which they are fitted to conduct us, I venture to believe that +there will not be found one who is not ready to labour hard in so +profitable a study, or at least to favour and aid with all his might +those who shall devote themselves to it with success. + +The height of my wishes is, that posterity may sometime behold the +happy issue of it, etc. + + + +TO THE MOST SERENE PRINCESS, + +ELIZABETH, ELDEST DAUGHTER OF FREDERICK, KING OF BOHEMIA, COUNT +PALATINE, AND ELECTOR OF THE SACRED ROMAN EMPIRE. + +MADAM,--The greatest advantage I have derived from the writings +which I have already published, has arisen from my having, through +means of them, become known to your Highness, and thus been +privileged to hold occasional converse with one in whom so many rare +and estimable qualities are united, as to lead me to believe I +should do service to the public by proposing them as an example to +posterity. It would ill become me to flatter, or to give expression +to anything of which I had no certain knowledge, especially in the +first pages of a work in which I aim at laying down the principles +of truth. And the generous modesty that is conspicuous in all your +actions, assures me that the frank and simple judgment of a man who +only writes what he believes will be more agreeable to you than the +ornate laudations of those who have studied the art of compliment. +For this reason, I will give insertion to nothing in this letter for +which I have not the certainty both of experience and reason; and in +the exordium, as in the rest of the work, I will write only as +becomes a philosopher. There is a vast difference between real and +apparent virtues; and there is also a great discrepancy between +those real virtues that proceed from an accurate knowledge of the +truth, and such as are accompanied with ignorance or error. The +virtues I call apparent are only, properly speaking, vices, which, +as they are less frequent than the vices that are opposed to them, +and are farther removed from them than the intermediate virtues, are +usually held in higher esteem than those virtues. Thus, because +those who fear dangers too much are more numerous than they who fear +them too little, temerity is frequently opposed to the vice of +timidity, and taken for a virtue, and is commonly more highly +esteemed than true fortitude. Thus, also, the prodigal are in +ordinary more praised than the liberal; and none more easily acquire +a great reputation for piety than the superstitious and +hypocritical. With regard to true virtues, these do not all proceed +from true knowledge, for there are some that likewise spring from +defect or error; thus, simplicity is frequently the source of +goodness, fear of devotion, and despair of courage. The virtues that +are thus accompanied with some imperfections differ from each other, +and have received diverse appellations. But those pure and perfect +virtues that arise from the knowledge of good alone are all of the +same nature, and may be comprised under the single term wisdom. For, +whoever owns the firm and constant resolution of always using his +reason as well as lies in his power, and in all his actions of doing +what he judges to be best, is truly wise, as far as his nature +permits; and by this alone he is just, courageous, temperate, and +possesses all the other virtues, but so well balanced as that none +of them appears more prominent than another: and for this reason, +although they are much more perfect than the virtues that blaze +forth through the mixture of some defect, yet, because the crowd +thus observes them less, they are not usually extolled so highly. +Besides, of the two things that are requisite for the wisdom thus +described, namely, the perception of the understanding and the +disposition of the will, it is only that which lies in the will +which all men can possess equally, inasmuch as the understanding of +some is inferior to that of others. But although those who have only +an inferior understanding may be as perfectly wise as their nature +permits, and may render themselves highly acceptable to God by their +virtue, provided they preserve always a firm and constant resolution +to do all that they shall judge to be right, and to omit nothing +that may lead them to the knowledge of the duties of which they are +ignorant; nevertheless, those who preserve a constant resolution of +performing the right, and are especially careful in instructing +themselves, and who possess also a highly perspicacious intellect, +arrive doubtless at a higher degree of wisdom than others; and I see +that these three particulars are found in great perfection in your +Highness. For, in the first place, your desire of self-instruction +is manifest, from the circumstance that neither the amusements of +the court, nor the accustomed mode of educating ladies, which +ordinarily condemns them to ignorance, have been sufficient to +prevent you from studying with much care all that is best in the +arts and sciences; and the incomparable perspicacity of your +intellect is evinced by this, that you penetrated the secrets of the +sciences and acquired an accurate knowledge of them in a very short +period. But of the vigour of your intellect I have a still stronger +proof, and one peculiar to myself, in that I have never yet met any +one who understood so generally and so well as yourself all that is +contained in my writings. For there are several, even among men of +the highest intellect and learning, who find them very obscure. And +I remark, in almost all those who are versant in Metaphysics, that +they are wholly disinclined from Geometry; and, on the other hand, +that the cultivators of Geometry have no ability for the +investigations of the First Philosophy: insomuch that I can say with +truth I know but one mind, and that is your own, to which both +studies are alike congenial, and which I therefore, with propriety, +designate incomparable. But what most of all enhances my admiration +is, that so accurate and varied an acquaintance with the whole +circle of the sciences is not found in some aged doctor who has +employed many years in contemplation, but in a Princess still young, +and whose countenance and years would more fitly represent one of +the Graces than a Muse or the sage Minerva. In conclusion, I not +only remark in your Highness all that is requisite on the part of +the mind to perfect and sublime wisdom, but also all that can be +required on the part of the will or the manners, in which benignity +and gentleness are so conjoined with majesty that, though fortune +has attacked you with continued injustice, it has failed either to +irritate or crush you. And this constrains me to such veneration +that I not only think this work due to you, since it treats of +philosophy which is the study of wisdom, but likewise feel not more +zeal for my reputation as a philosopher than pleasure in subscribing +myself,-- + +Of your most Serene Highness, The most devoted servant, + +DESCARTES. + + +OF THE PRINCIPLES OF HUMAN KNOWLEDGE. + + I. THAT in order to seek truth, it is necessary once in the course +of our life, to doubt, as far as possible, of all things. + +As we were at one time children, and as we formed various judgments +regarding the objects presented to our senses, when as yet we had +not the entire use of our reason, numerous prejudices stand in the +way of our arriving at the knowledge of truth; and of these it seems +impossible for us to rid ourselves, unless we undertake, once in our +lifetime, to doubt of all those things in which we may discover even +the smallest suspicion of uncertainty. + + II. That we ought also to consider as false all that is doubtful. + +Moreover, it will be useful likewise to esteem as false the things +of which we shall be able to doubt, that we may with greater +clearness discover what possesses most certainty and is the easiest +to know. + + III. That we ought not meanwhile to make use of doubt in the +conduct of life. + +In the meantime, it is to be observed that we are to avail ourselves +of this general doubt only while engaged in the contemplation of +truth. For, as far as concerns the conduct of life, we are very +frequently obliged to follow opinions merely probable, or even +sometimes, though of two courses of action we may not perceive more +probability in the one than in the other, to choose one or other, +seeing the opportunity of acting would not unfrequently pass away +before we could free ourselves from our doubts. + + IV. Why we may doubt of sensible things. + +Accordingly, since we now only design to apply ourselves to the +investigation of truth, we will doubt, first, whether of all the +things that have ever fallen under our senses, or which we have ever +imagined, any one really exist; in the first place, because we know +by experience that the senses sometimes err, and it would be +imprudent to trust too much to what has even once deceived us; +secondly, because in dreams we perpetually seem to perceive or +imagine innumerable objects which have no existence. And to one who +has thus resolved upon a general doubt, there appear no marks by +which he can with certainty distinguish sleep from the waking state. + + V. Why we may also doubt of mathematical demonstrations. + +We will also doubt of the other things we have before held as most +certain, even of the demonstrations of mathematics, and of their +principles which we have hitherto deemed self-evident; in the first +place, because we have sometimes seen men fall into error in such +matters, and admit as absolutely certain and self evident what to us +appeared false, but chiefly because we have learnt that God who +created us is all-powerful; for we do not yet know whether perhaps +it was his will to create us so that we are always deceived, even in +the things we think we know best: since this does not appear more +impossible than our being occasionally deceived, which, however, as +observation teaches us, is the case. And if we suppose that an all- +powerful God is not the author of our being, and that we exist of +ourselves or by some other means, still, the less powerful we +suppose our author to be, the greater reason will we have for +believing that we are not so perfect as that we may not be +continually deceived. + + VI. That we possess a free-will, by which we can withhold our +assent from what is doubtful, and thus avoid error. + +But meanwhile, whoever in the end may be the author of our being, +and however powerful and deceitful he may be, we are nevertheless +conscious of a freedom, by which we can refrain from admitting to a +place in our belief aught that is not manifestly certain and +undoubted, and thus guard against ever being deceived. + + VII. That we cannot doubt of our existence while we doubt, and that +this is the first knowledge we acquire when we philosophize in +order. + +While we thus reject all of which we can entertain the smallest +doubt, and even imagine that it is false, we easily indeed suppose +that there is neither God, nor sky, nor bodies, and that we +ourselves even have neither hands nor feet, nor, finally, a body; +but we cannot in the same way suppose that we are not while we doubt +of the truth of these things; for there is a repugnance in +conceiving that what thinks does not exist at the very time when it +thinks. Accordingly, the knowledge, _I_ THINK, THEREFORE _I_ AM, is +the first and most certain that occurs to one who philosophizes +orderly. + + VIII. That we hence discover the distinction between the mind and +the body, or between a thinking and corporeal thing. + +And this is the best mode of discovering the nature of the mind, and +its distinctness from the body: for examining what we are, while +supposing, as we now do, that there is nothing really existing apart +from our thought, we clearly perceive that neither extension, nor +figure, nor local motion,[Footnote: Instead of "local motion," the +French has "existence in any place."] nor anything similar that can +be attributed to body, pertains to our nature, and nothing save +thought alone; and, consequently, that the notion we have of our +mind precedes that of any corporeal thing, and is more certain, +seeing we still doubt whether there is any body in existence, while +we already perceive that we think. + + IX. What thought (COGITATIO) is. + +By the word thought, I understand all that which so takes place in +us that we of ourselves are immediately conscious of it; and, +accordingly, not only to understand (INTELLIGERE, ENTENDRE), to will +(VELLE), to imagine (IMAGINARI), but even to perceive (SENTIRE, +SENTIR), are here the same as to think (COGITARE, PENSER). For if I +say, I see, or, I walk, therefore I am; and if I understand by +vision or walking the act of my eyes or of my limbs, which is the +work of the body, the conclusion is not absolutely certain, because, +as is often the case in dreams, I may think that I see or walk, +although I do not open my eyes or move from my place, and even, +perhaps, although I have no body: but, if I mean the sensation +itself, or consciousness of seeing or walking, the knowledge is +manifestly certain, because it is then referred to the mind, which +alone perceives or is conscious that it sees or walks. [Footnote: In +the French, "which alone has the power of perceiving, or of being +conscious in any other way whatever."] + + X. That the notions which are simplest and self-evident, are +obscured by logical definitions; and that such are not to be +reckoned among the cognitions acquired by study, [but as born with +us]. + +I do not here explain several other terms which I have used, or +design to use in the sequel, because their meaning seems to me +sufficiently self-evident. And I frequently remarked that +philosophers erred in attempting to explain, by logical definitions, +such truths as are most simple and self-evident; for they thus only +rendered them more obscure. And when I said that the proposition, +_I_ THINK, THEREFORE _I_ AM, is of all others the first and most +certain which occurs to one philosophizing orderly, I did not +therefore deny that it was necessary to know what thought, +existence, and certitude are, and the truth that, in order to think +it is necessary to be, and the like; but, because these are the most +simple notions, and such as of themselves afford the knowledge of +nothing existing, I did not judge it proper there to enumerate them. + + XI. How we can know our mind more clearly than our body. + +But now that it may be discerned how the knowledge we have of the +mind not only precedes, and has greater certainty, but is even +clearer, than that we have of the body, it must be remarked, as a +matter that is highly manifest by the natural light, that to nothing +no affections or qualities belong; and, accordingly, that where we +observe certain affections, there a thing or substance to which +these pertain, is necessarily found. The same light also shows us +that we know a thing or substance more clearly in proportion as we +discover in it a greater number of qualities. Now, it is manifest +that we remark a greater number of qualities in our mind than in any +other thing; for there is no occasion on which we know anything +whatever when we are not at the same time led with much greater +certainty to the knowledge of our own mind. For example, if I judge +that there is an earth because I touch or see it, on the same +ground, and with still greater reason, I must be persuaded that my +mind exists; for it may be, perhaps, that I think I touch the earth +while there is one in existence; but it is not possible that I +should so judge, and my mind which thus judges not exist; and the +same holds good of whatever object is presented to our mind. + + XII. How it happens that every one does not come equally to know +this. + +Those who have not philosophized in order have had other opinions on +this subject, because they never distinguished with sufficient care +the mind from the body. For, although they had no difficulty in +believing that they themselves existed, and that they had a higher +assurance of this than of any other thing, nevertheless, as they did +not observe that by THEMSELVES, they ought here to understand their +MINDS alone [when the question related to metaphysical certainty]; +and since, on the contrary, they rather meant their bodies which +they saw with their eyes, touched with their hands, and to which +they erroneously attributed the faculty of perception, they were +prevented from distinctly apprehending the nature of the mind. + + XIII. In what sense the knowledge of other things depends upon the +knowledge of God. + +But when the mind, which thus knows itself but is still in doubt as +to all other things, looks around on all sides, with a view to the +farther extension of its knowledge, it first of all discovers within +itself the ideas of many things; and while it simply contemplates +them, and neither affirms nor denies that there is anything beyond +itself corresponding to them, it is in no danger of erring. The mind +also discovers certain common notions out of which it frames various +demonstrations that carry conviction to such a degree as to render +doubt of their truth impossible, so long as we give attention to +them. For example, the mind has within itself ideas of numbers and +figures, and it has likewise among its common notions the principle +THAT IF EQUALS BE ADDED TO EQUALS THE WHOLES WILL BE EQUAL and the +like; from which it is easy to demonstrate that the three angles of +a triangle are equal to two right angles, etc. Now, so long as we +attend to the premises from which this conclusion and others similar +to it were deduced, we feel assured of their truth; but, as the mind +cannot always think of these with attention, when it has the +remembrance of a conclusion without recollecting the order of its +deduction, and is uncertain whether the author of its being has +created it of a nature that is liable to be deceived, even in what +appears most evident, it perceives that there is just ground to +distrust the truth of such conclusions, and that it cannot possess +any certain knowledge until it has discovered its author. + + XIV. That we may validly infer the existence of God from necessary +existence being comprised in the concept we have of him. + +When the mind afterwards reviews the different ideas that are in it, +it discovers what is by far the chief among them--that of a Being +omniscient, all-powerful, and absolutely perfect; and it observes +that in this idea there is contained not only possible and +contingent existence, as in the ideas of all other things which it +clearly perceives, but existence absolutely necessary and eternal. +And just as because, for example, the equality of its three angles +to two right angles is necessarily comprised in the idea of a +triangle, the mind is firmly persuaded that the three angles of a +triangle are equal to two right angles; so, from its perceiving +necessary and eternal existence to be comprised in the idea which it +has of an all-perfect Being, it ought manifestly to conclude that +this all-perfect Being exists. + + XV. That necessary existence is not in the same way comprised in +the notions which we have of other things, but merely contingent +existence. + +The mind will be still more certain of the truth of this conclusion, +if it consider that it has no idea of any other thing in which it +can discover that necessary existence is contained; for, from this +circumstance alone, it will discern that the idea of an all-perfect +Being has not been framed by itself, and that it does not represent +a chimera, but a true and immutable nature, which must exist since +it can only be conceived as necessarily existing. + + XVI. That prejudices hinder many from clearly knowing the necessity +of the existence of God. + +Our mind would have no difficulty in assenting to this truth, if it +were, first of all, wholly free from prejudices; but as we have been +accustomed to distinguish, in all other things, essence from +existence, and to imagine at will many ideas of things which neither +are nor have been, it easily happens, when we do not steadily fix +our thoughts on the contemplation of the all-perfect Being, that a +doubt arises as to whether the idea we have of him is not one of +those which we frame at pleasure, or at least of that class to whose +essence existence does not pertain. + + XVII. That the greater objective (representative) perfection there +is in our idea of a thing, the greater also must be the perfection +of its cause. + +When we further reflect on the various ideas that are in us, it is +easy to perceive that there is not much difference among them, when +we consider them simply as certain modes of thinking, but that they +are widely different, considered in reference to the objects they +represent; and that their causes must be so much the more perfect +according to the degree of objective perfection contained in them. +[Footnote: "as what they represent of their object has more +perfection."--FRENCH.] For there is no difference between this and +the case of a person who has the idea of a machine, in the +construction of which great skill is displayed, in which +circumstances we have a right to inquire how he came by this idea, +whether, for example, he somewhere saw such a machine constructed by +another, or whether he was so accurately taught the mechanical +sciences, or is endowed with such force of genius, that he was able +of himself to invent it, without having elsewhere seen anything like +it; for all the ingenuity which is contained in the idea objectively +only, or as it were in a picture, must exist at least in its first +and chief cause, whatever that may be, not only objectively or +representatively, but in truth formally or eminently. + + XVIII. That the existence of God may be again inferred from the +above. + +Thus, because we discover in our minds the idea of God, or of an +all-perfect Being, we have a right to inquire into the source whence +we derive it; and we will discover that the perfections it +represents are so immense as to render it quite certain that we +could only derive it from an all-perfect Being; that is, from a God +really existing. For it is not only manifest by the natural light +that nothing cannot be the cause of anything whatever, and that the +more perfect cannot arise from the less perfect, so as to be thereby +produced as by its efficient and total cause, but also that it is +impossible we can have the idea or representation of anything +whatever, unless there be somewhere, either in us or out of us, an +original which comprises, in reality, all the perfections that are +thus represented to us; but, as we do not in any way find in +ourselves those absolute perfections of which we have the idea, we +must conclude that they exist in some nature different from ours, +that is, in God, or at least that they were once in him; and it most +manifestly follows [from their infinity] that they are still there. + + XIX. That, although we may not comprehend the nature of God, there +is yet nothing which we know so clearly as his perfections. + +This will appear sufficiently certain and manifest to those who have +been accustomed to contemplate the idea of God, and to turn their +thoughts to his infinite perfections; for, although we may not +comprehend them, because it is of the nature of the infinite not to +be comprehended by what is finite, we nevertheless conceive them +more clearly and distinctly than material objects, for this reason, +that, being simple, and unobscured by limits,[Footnote: After +LIMITS, "what of them we do conceive is much less confused. There +is, besides, no speculation more calculated to aid in perfecting our +understanding, and which is more important than this, inasmuch as +the consideration of an object that has no limits to its perfections +fills us with satisfaction and assurance."-FRENCH.] they occupy our +mind more fully. + + XX. That we are not the cause of ourselves, but that this is God, +and consequently that there is a God. + +But, because every one has not observed this, and because, when we +have an idea of any machine in which great skill is displayed, we +usually know with sufficient accuracy the manner in which we +obtained it, and as we cannot even recollect when the idea we have +of a God was communicated to us by him, seeing it was always in our +minds, it is still necessary that we should continue our review, and +make inquiry after our author, possessing, as we do, the idea of the +infinite perfections of a God: for it is in the highest degree +evident by the natural light, that that which knows something more +perfect than itself, is not the source of its own being, since it +would thus have given to itself all the perfections which it knows; +and that, consequently, it could draw its origin from no other being +than from him who possesses in himself all those perfections, that +is, from God. + + XXI. That the duration alone of our life is sufficient to +demonstrate the existence of God. + +The truth of this demonstration will clearly appear, provided we +consider the nature of time, or the duration of things; for this is +of such a kind that its parts are not mutually dependent, and never +co-existent; and, accordingly, from the fact that we now are, it +does not necessarily follow that we shall be a moment afterwards, +unless some cause, viz., that which first produced us, shall, as it +were, continually reproduce us, that is, conserve us. For we easily +understand that there is no power in us by which we can conserve +ourselves, and that the being who has so much power as to conserve +us out of himself, must also by so much the greater reason conserve +himself, or rather stand in need of being conserved by no one +whatever, and, in fine, be God. + + XXII. That in knowing the existence of God, in the manner here +explained, we likewise know all his attributes, as far as they can +be known by the natural light alone. + +There is the great advantage in proving the existence of God in this +way, viz., by his idea, that we at the same time know what he is, as +far as the weakness of our nature allows; for, reflecting on the +idea we have of him which is born with us, we perceive that he is +eternal, omniscient, omnipotent, the source of all goodness and +truth, creator of all things, and that, in fine, he has in himself +all that in which we can clearly discover any infinite perfection or +good that is not limited by any imperfection. + + XXIII. That God is not corporeal, and does not perceive by means of +senses as we do, or will the evil of sin. + +For there are indeed many things in the world that are to a certain +extent imperfect or limited, though possessing also some perfection; +and it is accordingly impossible that any such can be in God. Thus, +looking to corporeal nature,[Footnote: In the French, "since +extension constitutes the nature of body."] since divisibility is +included in local extension, and this indicates imperfection, it is +certain that God is not body. And although in men it is to some +degree a perfection to be capable of perceiving by means of the +senses, nevertheless since in every sense there is passivity +[Footnote: In the French, "because our perceptions arise from +impressions made upon us from another source," i.e., than +ourselves.] which indicates dependency, we must conclude that God is +in no manner possessed of senses, and that he only understands and +wills, not, however, like us, by acts in any way distinct, but +always by an act that is one, identical, and the simplest possible, +understands, wills, and operates all, that is, all things that in +reality exist; for he does not will the evil of sin, seeing this is +but the negation of being. + + XXIV. That in passing from the knowledge of God to the knowledge of +the creatures, it is necessary to remember that our understanding is +finite, and the power of God infinite. + +But as we know that God alone is the true cause of all that is or +can be, we will doubtless follow the best way of philosophizing, if, +from the knowledge we have of God himself, we pass to the +explication of the things which he has created, and essay to deduce +it from the notions that are naturally in our minds, for we will +thus obtain the most perfect science, that is, the knowledge of +effects through their causes. But that we may be able to make this +attempt with sufficient security from error, we must use the +precaution to bear in mind as much as possible that God, who is the +author of things, is infinite, while we are wholly finite. + + XXV. That we must believe all that God has revealed, although it +may surpass the reach of our faculties. + +Thus, if perhaps God reveal to us or others, matters concerning +himself which surpass the natural powers of our mind, such as the +mysteries of the incarnation and of the trinity, we will not refuse +to believe them, although we may not clearly understand them; nor +will we be in any way surprised to find in the immensity of his +nature, or even in what he has created, many things that exceed our +comprehension. + + XXVI. That it is not needful to enter into disputes [Footnote: "to +essay to comprehend the infinite."--FRENCH.] regarding the infinite, +but merely to hold all that in which we can find no limits as +indefinite, such as the extension of the world, the divisibility of +the parts of matter, the number of the stars, etc. + +We will thus never embarrass ourselves by disputes about the +infinite, seeing it would be absurd for us who are finite to +undertake to determine anything regarding it, and thus as it were to +limit it by endeavouring to comprehend it. We will accordingly give +ourselves no concern to reply to those who demand whether the half +of an infinite line is also infinite, and whether an infinite number +is even or odd, and the like, because it is only such as imagine +their minds to be infinite who seem bound to entertain questions of +this sort. And, for our part, looking to all those things in which +in certain senses, we discover no limits, we will not, therefore, +affirm that they are infinite, but will regard them simply as +indefinite. Thus, because we cannot imagine extension so great that +we cannot still conceive greater, we will say that the magnitude of +possible things is indefinite, and because a body cannot be divided +into parts so small that each of these may not be conceived as again +divided into others still smaller, let us regard quantity as +divisible into parts whose number is indefinite; and as we cannot +imagine so many stars that it would seem impossible for God to +create more, let us suppose that their number is indefinite, and so +in other instances. + + XXVII. What difference there is between the indefinite and the +infinite. + +And we will call those things indefinite rather than infinite, with +the view of reserving to God alone the appellation of infinite; in +the first place, because not only do we discover in him alone no +limits on any side, but also because we positively conceive that he +admits of none; and in the second place, because we do not in the +same way positively conceive that other things are in every part +unlimited, but merely negatively admit that their limits, if they +have any, cannot be discovered by us. + + XXVIII. That we must examine, not the final, but the efficient, +causes of created things. + +Likewise, finally, we will not seek reasons of natural things from +the end which God or nature proposed to himself in their creation +(i. e., final causes), [Footnote: "We will not stop to consider the +ends which God proposed to himself in the creation of the world, and +we will entirely reject from our philosophy the search of final +causes!"--French.] for we ought not to presume so far as to think +that we are sharers in the counsels of Deity, but, considering him +as the efficient cause of all things, let us endeavour to discover +by the natural light [Footnote: "Faculty of reasoning."--FRENCH.] +which he has planted in us, applied to those of his attributes of +which he has been willing we should have some knowledge, what must +be concluded regarding those effects we perceive by our senses; +bearing in mind, however, what has been already said, that we must +only confide in this natural light so long as nothing contrary to +its dictates is revealed by God himself. [Footnote: The last clause, +beginning "bearing in mind." is omitted in the French.] + + XXIX. That God is not the cause of our errors. + +The first attribute of God which here falls to be considered, is +that he is absolutely veracious and the source of all light, so that +it is plainly repugnant for him to deceive us, or to be properly and +positively the cause of the errors to which we are consciously +subject; for although the address to deceive seems to be some mark +of subtlety of mind among men, yet without doubt the will to deceive +only proceeds from malice or from fear and weakness, and +consequently cannot be attributed to God. + + XXX. That consequently all which we clearly perceive is true, and +that we are thus delivered from the doubts above proposed. + +Whence it follows, that the light of nature, or faculty of knowledge +given us by God, can never compass any object which is not true, in +as far as it attains to a knowledge of it, that is, in as far as the +object is clearly and distinctly apprehended. For God would have +merited the appellation of a deceiver if he had given us this +faculty perverted, and such as might lead us to take falsity for +truth [when we used it aright]. Thus the highest doubt is removed, +which arose from our ignorance on the point as to whether perhaps +our nature was such that we might be deceived even in those things +that appear to us the most evident. The same principle ought also to +be of avail against all the other grounds of doubting that have been +already enumerated. For mathematical truths ought now to be above +suspicion, since these are of the clearest. And if we perceive +anything by our senses, whether while awake or asleep, we will +easily discover the truth provided we separate what there is of +clear and distinct in the knowledge from what is obscure and +confused. There is no need that I should here say more on this +subject, since it has already received ample treatment in the +metaphysical Meditations; and what follows will serve to explain it +still more accurately. + + XXXI. That our errors are, in respect of God, merely negations, +but, in respect of ourselves, privations. + +But as it happens that we frequently fall into error, although God +is no deceiver, if we desire to inquire into the origin and cause of +our errors, with a view to guard against them, it is necessary to +observe that they depend less on our understanding than on our will, +and that they have no need of the actual concourse of God, in order +to their production; so that, when considered in reference to God, +they are merely negations, but in reference to ourselves, +privations. + + XXXII. That there are only two modes of thinking in us, viz., the +perception of the understanding and the action of the will. + +For all the modes of thinking of which we are conscious may be +referred to two general classes, the one of which is the perception +or operation of the understanding, and the other the volition or +operation of the will. Thus, to perceive by the senses (SENTIRE), to +imagine, and to conceive things purely intelligible, are only +different modes of perceiving (PERCIP IENDI); but to desire, to be +averse from, to affirm, to deny, to doubt, are different modes of +willing. + + XXXIII. That we never err unless when we judge of something which +we do not sufficiently apprehend. + +When we apprehend anything we are in no danger of error, if we +refrain from judging of it in any way; and even when we have formed +a judgment regarding it, we would never fall into error, provided we +gave our assent only to what we clearly and distinctly perceived; +but the reason why we are usually deceived, is that we judge without +possessing an exact knowledge of that of which we judge. + + XXXIV. That the will as well as the understanding is required for +judging. + +I admit that the understanding is necessary for judging, there being +no room to suppose that we can judge of that which we in no way +apprehend; but the will also is required in order to our assenting +to what we have in any degree perceived. It is not necessary, +however, at least to form any judgment whatever, that we have an +entire and perfect apprehension of a thing; for we may assent to +many things of which we have only a very obscure and confused +knowledge. + + XXXV. That the will is of greater extension than the understanding, +and is thus the source of our errors. + +Further, the perception of the intellect extends only to the few +things that are presented to it, and is always very limited: the +will, on the other hand, may, in a certain sense, be said to be +infinite, because we observe nothing that can be the object of the +will of any other, even of the unlimited will of God, to which ours +cannot also extend, so that we easily carry it beyond the objects we +clearly perceive; and when we do this, it is not wonderful that we +happen to be deceived. + + XXXVI. That our errors cannot be imputed to God. + +But although God has not given us an omniscient understanding, he is +not on this account to be considered in any wise the author of our +errors, for it is of the nature of created intellect to be finite, +and of finite intellect not to embrace all things. + + XXXVII. That the chief perfection of man is his being able to act +freely or by will, and that it is this which renders him worthy of +praise or blame. + +That the will should be the more extensive is in harmony with its +nature: and it is a high perfection in man to be able to act by +means of it, that is, freely; and thus in a peculiar way to be the +master of his own actions, and merit praise or blame. For self- +acting machines are not commended because they perform with +exactness all the movements for which they were adapted, seeing +their motions are carried on necessarily; but the maker of them is +praised on account of the exactness with which they were framed, +because he did not act of necessity, but freely; and, on the same +principle, we must attribute to ourselves something more on this +account, that when we embrace truth, we do so not of necessity, but +freely. + + XXXVIII. That error is a defect in our mode of acting, not in our +nature; and that the faults of their subjects may be frequently +attributed to other masters, but never to God. + +It is true, that as often as we err, there is some defect in our +mode of action or in the use of our liberty, but not in our nature, +because this is always the same, whether our judgments be true or +false. And although God could have given to us such perspicacity of +intellect that we should never have erred, we have, notwithstanding, +no right to demand this of him; for, although with us he who was +able to prevent evil and did not is held guilty of it, God is not in +the same way to be reckoned responsible for our errors because he +had the power to prevent them, inasmuch as the dominion which some +men possess over others has been instituted for the purpose of +enabling them to hinder those under them from doing evil, whereas +the dominion which God exercises over the universe is perfectly +absolute and free. For this reason we ought to thank him for the +goods he has given us, and not complain that he has not blessed us +with all which we know it was in his power to impart. + + XXXIX. That the liberty of our will is self-evident. + +Finally, it is so manifest that we possess a free will, capable of +giving or withholding its assent, that this truth must be reckoned +among the first and most common notions which are born with us. +This, indeed, has already very clearly appeared, for when essaying +to doubt of all things, we went so far as to suppose even that he +who created us employed his limitless power in deceiving us in every +way, we were conscious nevertheless of being free to abstain from +believing what was not in every respect certain and undoubted. But +that of which we are unable to doubt at such a time is as self- +evident and clear as any thing we can ever know. + + XL. That it is likewise certain that God has fore-ordained all +things. + +But because what we have already discovered of God, gives us the +assurance that his power is so immense that we would sin in thinking +ourselves capable of ever doing anything which he had not ordained +beforehand, we should soon be embarrassed in great difficulties if +we undertook to harmonise the pre-ordination of God with the freedom +of our will, and endeavoured to comprehend both truths at once. + + XLI. How the freedom of our will may be reconciled with the Divine +pre-ordination. + +But, in place of this, we will be free from these embarrassments if +we recollect that our mind is limited, while the power of God, by +which he not only knew from all eternity what is or can be, but also +willed and pre-ordained it, is infinite. It thus happens that we +possess sufficient intelligence to know clearly and distinctly that +this power is in God, but not enough to comprehend how he leaves the +free actions of men indeterminate} and, on the other hand, we have +such consciousness of the liberty and indifference which exists in +ourselves, that there is nothing we more clearly or perfectly +comprehend: [so that the omnipotence of God ought not to keep us +from believing it]. For it would be absurd to doubt of that of which +we are fully conscious, and which we experience as existing in +ourselves, because we do not comprehend another matter which, from +its very nature, we know to be incomprehensible. + + XLII. How, although we never will to err, it is nevertheless by our +will that we do err. + +But now since we know that all our errors depend upon our will, and +as no one wishes to deceive himself, it may seem wonderful that +there is any error in our judgments at all. It is necessary to +remark, however, that there is a great difference between willing to +be deceived, and willing to yield assent to opinions in which it +happens that error is found. For though there is no one who +expressly wishes to fall into error, we will yet hardly find any one +who is not ready to assent to things in which, unknown to himself, +error lurks; and it even frequently happens that it is the desire +itself of following after truth that leads those not fully aware of +the order in which it ought to be sought for, to pass judgment on +matters of which they have no adequate knowledge, and thus to fall +into error. + + XLIII. That we shall never err if we give our assent only to what +we clearly and distinctly perceive. + +But it is certain we will never admit falsity for truth, so long as +we judge only of that which we clearly and distinctly perceive; +because, as God is no deceiver, the faculty of knowledge which he +has given us cannot be fallacious, nor, for the same reason, the +faculty of will, when we do not extend it beyond the objects we +clearly know. And even although this truth could not be established +by reasoning, the minds of all have been so impressed by nature as +spontaneously to assent to whatever is clearly perceived, and to +experience an impossibility to doubt of its truth. + + XLIV. That we uniformly judge improperly when we assent to what we +do not clearly perceive, although our judgment may chance to be +true; and that it is frequently our memory which deceives us by +leading us to believe that certain things were formerly sufficiently +understood by us. + +It is likewise certain that, when we approve of any reason which we +do not apprehend, we are either deceived, or, if we stumble on the +truth, it is only by chance, and thus we can never possess the +assurance that we are not in error. I confess it seldom happens that +we judge of a thing when we have observed we do not apprehend it, +because it is a dictate of the natural light never to judge of what +we do not know. But we most frequently err in this, that we presume +upon a past knowledge of much to which we give our assent, as to +something treasured up in the memory, and perfectly known to us; +whereas, in truth, we have no such knowledge. + + XLV. What constitutes clear and distinct perception. + +There are indeed a great many persons who, through their whole +lifetime, never perceive anything in a way necessary for judging of +it properly; for the knowledge upon which we can establish a certain +and indubitable judgment must be not only clear, but also, distinct. +I call that clear which is present and manifest to the mind giving +attention to it, just as we are said clearly to see objects when, +being present to the eye looking on, they stimulate it with +sufficient force. and it is disposed to regard them; but the +distinct is that which is so precise and different from all other +objects as to comprehend in itself only what is clear. [Footnote: +"what appears manifestly to him who considers it as he ought."-- +FRENCH.] + + XLVI. It is shown, from the example of pain, that a perception may +be clear without being distinct, but that it cannot be distinct +unless it is clear. + +For example, when any one feels intense pain, the knowledge which he +has of this pain is very clear, but it is not always distinct; for +men usually confound it with the obscure judgment they form +regarding its nature, and think that there is in the suffering part +something similar to the sensation of pain of which they are alone +conscious. And thus perception may be clear without being distinct, +but it can never be distinct without likewise being clear. + + XLVII. That, to correct the prejudices of our early years, we must +consider what is clear in each of our simple [Footnote: "first."-- +FRENCH.] notions. + +And, indeed, in our early years, the mind was so immersed in the +body, that, although it perceived many things with sufficient +clearness, it yet knew nothing distinctly; and since even at that +time we exercised our judgment in many matters, numerous prejudices +were thus contracted, which, by the majority, are never afterwards +laid aside. But that we may now be in a position to get rid of +these, I will here briefly enumerate all the simple notions of which +our thoughts are composed, and distinguish in each what is clear +from what is obscure, or fitted to lead into error. + + XLVIII. That all the objects of our knowledge are to be regarded +either (1) as things or the affections of things: or (2) as eternal +truths; with the enumeration of things. + +Whatever objects fall under our knowledge we consider either as +things or the affections of things,[Footnote: Things and the +affections of things are (in the French) equivalent to "what has +some (i.e., a REAL) existence," as opposed to the class of "eternal +truths," which have merely an IDEAL existence.] or as eternal truths +possessing no existence beyond our thought. Of the first class the +most general are substance, duration, order, number, and perhaps +also some others, which notions apply to all the kinds of things. I +do not, however, recognise more than two highest kinds (SUMMA +GENERA) of things; the first of intellectual things, or such as have +the power of thinking, including mind or thinking substance and its +properties; the second, of material things, embracing extended +substance, or body and its properties. Perception, volition, and all +modes as well of knowing as of willing, are related to thinking +substance; on the other hand, to extended substance we refer +magnitude, or extension in length, breadth, and depth, figure, +motion, situation, divisibility of parts themselves, and the like. +There are, however, besides these, certain things of which we have +an internal experience that ought not to be referred either to the +mind of itself, or to the body alone, but to the close and intimate +union between them, as will hereafter be shown in its place. Of this +class are the appetites of hunger and thirst, etc., and also the +emotions or passions of the mind which are not exclusively mental +affections, as the emotions of anger, joy, sadness, love, etc.; and, +finally, all the sensations, as of pain, titillation, light and +colours, sounds, smells, tastes, heat, hardness, and the other +tactile qualities. + + XLIX. That the eternal truths cannot be thus enumerated, but that +this is not necessary. + +What I have already enumerated we are to regard as things, or the +qualities or modes of things. We now come to speak of eternal +truths. When we apprehend that it is impossible a thing can arise +from nothing, this proposition, EX NIHILO NIHIL FIT, is not +considered as somewhat existing, or as the mode of a thing, but as +an eternal truth having its seat in our mind, and is called a common +notion or axiom. Of this class are the following:--It is impossible +the same thing can at once be and not be; what is done cannot be +undone; he who thinks must exist while he thinks; and innumerable +others, the whole of which it is indeed difficult to enumerate, but +this is not necessary, since, if blinded by no prejudices, we cannot +fail to know them when the occasion of thinking them occurs. + + L. That these truths are clearly perceived, but not equally by all +men, on account of prejudices. + +And, indeed, with regard to these common notions, it is not to be +doubted that they can be clearly and distinctly known, for otherwise +they would not merit this appellation: as, in truth, some of them +are not, with respect to all men, equally deserving of the name, +because they are not equally admitted by all: not, however, from +this reason, as I think, that the faculty of knowledge of one man +extends farther than that of another, but rather because these +common notions are opposed to the prejudices of some, who, on this +account, are not able readily to embrace them, even although others, +who are free from those prejudices, apprehend them with the greatest +clearness. + + LI. What substance is, and that the term is not applicable to God +and the creatures in the same sense. + +But with regard to what we consider as things or the modes of +things, it is worth while to examine each of them by itself. By +substance we can conceive nothing else than a thing which exists in +such a way as to stand in need of nothing beyond itself in order to +its existence. And, in truth, there can be conceived but one +substance which is absolutely independent, and that is God. We +perceive that all other things can exist only by help of the +concourse of God. And, accordingly, the term substance does not +apply to God and the creatures UNIVOCALLY, to adopt a term familiar +in the schools; that is, no signification of this word can be +distinctly understood which is common to God and them. + + LII. That the term is applicable univocally to the mind and the +body, and how substance itself is known. + +Created substances, however, whether corporeal or thinking, may be +conceived under this common concept; for these are things which, in +order to their existence, stand in need of nothing but the concourse +of God. But yet substance cannot be first discovered merely from its +being a thing which exists independently, for existence by itself is +not observed by us. We easily, however, discover substance itself +from any attribute of it, by this common notion, that of nothing +there are no attributes, properties, or qualities: for, from +perceiving that some attribute is present, we infer that some +existing thing or substance to which it may be attributed is also of +necessity present. + + LIII. That of every substance there is one principal attribute, as +thinking of the mind, extension of the body. + +But, although any attribute is sufficient to lead us to the +knowledge of substance, there is, however, one principal property of +every substance, which constitutes its nature or essence, and upon +which all the others depend. Thus, extension in length, breadth, and +depth, constitutes the nature of corporeal substance; and thought +the nature of thinking substance. For every other thing that can be +attributed to body, presupposes extension, and is only some mode of +an extended thing; as all the properties we discover in the mind are +only diverse modes of thinking. Thus, for example, we cannot +conceive figure unless in something extended, nor motion unless in +extended space, nor imagination, sensation, or will, unless in a +thinking thing. But, on the other hand, we can conceive extension +without figure or motion, and thought without imagination or +sensation, and so of the others; as is clear to any one who attends +to these matters. + + LIV. How we may have clear and distinct notions of the substance +which thinks, of that which is corporeal, and of God. + +And thus we may easily have two clear and distinct notions or ideas, +the one of created substance, which thinks, the other of corporeal +substance, provided we carefully distinguish all the attributes of +thought from those of extension. We may also have a clear and +distinct idea of an uncreated and independent thinking substance, +that is, of God, provided we do not suppose that this idea +adequately represents to us all that is in God, and do not mix up +with it anything fictitious, but attend simply to the characters +that are comprised in the notion we have of him, and which we +clearly know to belong to the nature of an absolutely perfect Being. +For no one can deny that there is in us such an idea of God, without +groundlessly supposing that there is no knowledge of God at all in +the human mind. + + LV. How duration, order, and number may be also distinctly +conceived. + +We will also have most distinct conceptions of duration, order, and +number, if, in place of mixing up with our notions of them that +which properly belongs to the concept of substance, we merely think +that the duration of a thing is a mode under which we conceive this +thing, in so far as it continues to exist; and, in like manner, that +order and number are not in reality different from things disposed +in order and numbered, but only modes under which we diversely +consider these things. + + LVI. What are modes, qualities, attributes. + +And, indeed, we here understand by modes the same with what we +elsewhere designate attributes or qualities. But when we consider +substance as affected or varied by them, we use the term modes; when +from this variation it may be denominated of such a kind, we adopt +the term qualities [to designate the different modes which cause it +to be so named]; and, finally, when we simply regard these modes as +in the substance, we call them attributes. Accordingly, since God +must be conceived as superior to change, it is not proper to say +that there are modes or qualities in him, but simply attributes; and +even in created things that which is found in them always in the +same mode, as existence and duration in the thing which exists and +endures, ought to be called attribute and not mode or quality. + + LVII. That some attributes exist in the things to which they are +attributed, and others only in our thought; and what duration and +time are. + +Of these attributes or modes there are some which exist in the +things themselves, and others that have only an existence in our +thought; thus, for example, time, which we distinguish from duration +taken in its generality, and call the measure of motion, is only a +certain mode under which we think duration itself, for we do not +indeed conceive the duration of things that are moved to be +different from the duration of things that are not moved: as is +evident from this, that if two bodies are in motion for an hour, the +one moving quickly and the other slowly, we do not reckon more time +in the one than in the other, although there may be much more motion +in the one of the bodies than in the other. But that we may +comprehend the duration of all things under a common measure, we +compare their duration with that of the greatest and most regular +motions that give rise to years and days, and which we call time; +hence what is so designated is nothing superadded to duration, taken +in its generality, but a mode of thinking. + + LVIII. That number and all universals are only modes of thought. + +In the same way number, when it is not considered as in created +things, but merely in the abstract or in general, is only a mode of +thinking; and the same is true of all those general ideas we call +universals. + + LIX. How universals are formed; and what are the five common, viz., +genus, species, difference, property, and accident. + +Universals arise merely from our making use of one and the same idea +in thinking of all individual objects between which there subsists a +certain likeness; and when we comprehend all the objects represented +by this idea under one name, this term likewise becomes universal. +For example, when we see two stones, and do not regard their nature +farther than to remark that there are two of them, we form the idea +of a certain number, which we call the binary; and when we +afterwards see two birds or two trees, and merely take notice of +them so far as to observe that there are two of them, we again take +up the same idea as before, which is, accordingly, universal; and we +likewise give to this number the same universal appellation of +binary. In the same way, when we consider a figure of three sides, +we form a certain idea, which we call the idea of a triangle, and we +afterwards make use of it as the universal to represent to our mind +all other figures of three sides. But when we remark more +particularly that of figures of three sides, some have a right angle +and others not, we form the universal idea of a right-angled +triangle, which being related to the preceding as more general, may +be called species; and the right angle the universal difference by +which right-angled triangles are distinguished from all others; and +farther, because the square of the side which sustains the right +angle is equal to the squares of the other two sides, and because +this property belongs only to this species of triangles, we may call +it the universal property of the species. Finally, if we suppose +that of these triangles some are moved and others not, this will be +their universal accident; and, accordingly, we commonly reckon five +universals, viz., genus, species, difference, property, accident. + + LX. Of distinctions; and first of the real. + +But number in things themselves arises from the distinction there is +between them: and distinction is threefold, viz., real, modal, and +of reason. The real properly subsists between two or more +substances; and it is sufficient to assure us that two substances +are really mutually distinct, if only we are able clearly and +distinctly to conceive the one of them without the other. For the +knowledge we have of God renders it certain that he can effect all +that of which we have a distinct idea: wherefore, since we have now, +for example, the idea of an extended and corporeal substance, though +we as yet do not know with certainty whether any such thing is +really existent, nevertheless, merely because we have the idea of +it, we may be assured that such may exist; and, if it really exists, +that every part which we can determine by thought must be really +distinct from the other parts of the same substance. In the same +way, since every one is conscious that he thinks, and that he in +thought can exclude from himself every other substance, whether +thinking or extended, it is certain that each of us thus considered +is really distinct from every other thinking and corporeal +substance. And although we suppose that God united a body to a soul +so closely that it was impossible to form a more intimate union, and +thus made a composite whole, the two substances would remain really +distinct, notwithstanding this union; for with whatever tie God +connected them, he was not able to rid himself of the power he +possessed of separating them, or of conserving the one apart from +the other, and the things which God can separate or conserve +separately are really distinct. + + LXI. Of the modal distinction. + +There are two kinds of modal distinctions, viz., that between the +mode properly so-called and the substance of which it is a mode, and +that between two modes of the same substance. Of the former we have +an example in this, that we can clearly apprehend substance apart +from the mode which we say differs from it; while, on the other +hand, we cannot conceive this mode without conceiving the substance +itself. There is, for example, a modal distinction between figure or +motion and corporeal substance in which both exist; there is a +similar distinction between affirmation or recollection and the +mind. Of the latter kind we have an illustration in our ability to +recognise the one of two modes apart from the other, as figure apart +from motion, and motion apart from figure; though we cannot think of +either the one or the other without thinking of the common substance +in which they adhere. If, for example, a stone is moved, and is +withal square, we can, indeed, conceive its square figure without +its motion, and reciprocally its motion without its square figure; +but we can conceive neither this motion nor this figure apart from +the substance of the stone. As for the distinction according to +which the mode of one substance is different from another substance, +or from the mode of another substance, as the motion of one body is +different from another body or from the mind, or as motion is +different from doubt, it seems to me that it should be called real +rather than modal, because these modes cannot be clearly conceived +apart from the really distinct substances of which they are the +modes. + + LXII. Of the distinction of reason (logical distinction). + +Finally, the distinction of reason is that between a substance and +some one of its attributes, without which it is impossible, however, +we can have a distinct conception of the substance itself; or +between two such attributes of a common substance, the one of which +we essay to think without the other. This distinction is manifest +from our inability to form a clear and distinct idea of such +substance, if we separate from it such attribute; or to have a clear +perception of the one of two such attributes if we separate it from +the other. For example, because any substance which ceases to endure +ceases also to exist, duration is not distinct from substance except +in thought (RATIONE); and in general all the modes of thinking which +we consider as in objects differ only in thought, as well from the +objects of which they are thought as from each other in a common +object.[Footnote: "and generally all the attributes that lead us to +entertain different thoughts of the same thing, such as, for +example, the extension of body and its property of divisibility, do +not differ from the body which is to us the object of them, or from +each other, unless as we sometimes confusedly think the one without +thinking the other."--FRENCH.] It occurs, indeed, to me that I have +elsewhere classed this kind of distinction with the modal (viz., +towards the end of the Reply to the First Objections to the +Meditations on the First Philosophy); but there it was only +necessary to treat of these distinctions generally, and it was +sufficient for my purpose at that time simply to distinguish both of +them from the real. + + LXIII. How thought and extension may be distinctly known, as +constituting, the one the nature of mind, the other that of body. + +Thought and extension may be regarded as constituting the natures of +intelligent and corporeal substance; and then they must not be +otherwise conceived than as the thinking and extended substances +themselves, that is, as mind and body, which in this way are +conceived with the greatest clearness and distinctness. Moreover, we +more easily conceive extended or thinking substance than substance +by itself, or with the omission of its thinking or extension. For +there is some difficulty in abstracting the notion of substance from +the notions of thinking and extension, which, in truth, are only +diverse in thought itself (i.e., logically different); and a concept +is not more distinct because it comprehends fewer properties, but +because we accurately distinguish what is comprehended in it from +all other notions. + + LXIV. How these may likewise be distinctly conceived as modes of +substance. + +Thought and extension may be also considered as modes of substance; +in as far, namely, as the same mind may have many different +thoughts, and the same body, with its size unchanged, may be +extended in several diverse ways, at one time more in length and +less in breadth or depth, and at another time more in breadth and +less in length; and then they are modally distinguished from +substance, and can be conceived not less clearly and distinctly, +provided they be not regarded as substances or things separated from +others, but simply as modes of things. For by regarding them as in +the substances of which they are the modes, we distinguish them from +these substances, and take them for what in truth they are: whereas, +on the other hand, if we wish to consider them apart from the +substances in which they are, we should by this itself regard them +as self-subsisting things, and thus confound the ideas of mode and +substance. + + LXV. How we may likewise know their modes. + +In the same way we will best apprehend the diverse modes of thought, +as intellection, imagination, recollection, volition, etc., and also +the diverse modes of extension, or those that belong to extension, +as all figures, the situation of parts and their motions, provided +we consider them simply as modes of the things in which they are; +and motion as far as it is concerned, provided we think merely of +locomotion, without seeking to know the force that produces it, and +which nevertheless I will essay to explain in its own place. + + LXVI. How our sensations, affections, and appetites may be clearly +known, although we are frequently wrong in our judgments regarding +them. + +There remain our sensations, affections, and appetites, of which we +may also have a clear knowledge, if we take care to comprehend in +the judgments we form of them only that which is precisely contained +in our perception of them, and of which we are immediately +conscious. There is, however, great difficulty in observing this, at +least in respect of sensations; because we have all, without +exception, from our youth judged that all the things we perceived by +our senses had an existence beyond our thought, and that they were +entirely similar to the sensations, that is, perceptions, we had of +them. Thus when, for example, we saw a certain colour, we thought we +saw something occupying a place out of us, and which was entirely +similar to that idea of colour we were then conscious of; and from +the habit of judging in this way, we seemed to see this so clearly +and distinctly that we esteemed it (i.e., the externality of the +colour) certain and indubitable. + + LXVII. That we are frequently deceived in our judgments regarding +pain itself. + +The same prejudice has place in all our other sensations, even in +those of titillation and pain. For though we are not in the habit of +believing that there exist out of us objects that resemble +titillation and pain, we do not nevertheless consider these +sensations as in the mind alone, or in our perception, but as in the +hand, or foot, or some other part of our body. There is no reason, +however, to constrain us to believe that the pain, for example, +which we feel, as it were, in the foot is something out of the mind +existing in the foot, or that the light which we see, as it were, in +the sun exists in the sun as it is in us. Both these beliefs are +prejudices of our early years, as will clearly appear in the sequel. + + LXVIII. How in these things what we clearly conceive is to be +distinguished from that in which we may be deceived. + +But that we may distinguish what is clear in our sensations from +what is obscure, we ought most carefully to observe that we possess +a clear and distinct knowledge of pain, colour, and other things of +this sort, when we consider them simply as sensations or thoughts; +but that, when they are judged to be certain things subsisting +beyond our mind, we are wholly unable to form any conception of +them. Indeed, when any one tells us that he sees colour in a body or +feels pain in one of his limbs, this is exactly the same as if he +said that he there saw or felt something of the nature of which he +was entirely ignorant, or that he did not know what he saw or felt. +For although, when less attentively examining his thoughts, a person +may easily persuade himself that he has some knowledge of it, since +he supposes that there is something resembling that sensation of +colour or of pain of which he is conscious; yet, if he reflects on +what the sensation of colour or pain represents to him as existing +in a coloured body or in a wounded member, he will find that of such +he has absolutely no knowledge. + + LXIX. That magnitude, figure, etc., are known far differently from +colour, pain, etc. + +What we have said above will be more manifest; especially if we +consider that size in the body perceived, figure, motion (at least +local, for philosophers by fancying other kinds of motion have +rendered its nature less intelligible to themselves), the situation +of parts, duration, number, and those other properties which, as we +have already said, we clearly perceive in all bodies, are known by +us in a way altogether different from that in which we know what +colour is in the same body, or pain, smell, taste, or any other of +those properties which I have said above must be referred to the +senses. For although when we see a body we are not less assured of +its existence from its appearing figured than from its appearing +coloured,[Footnote: "by the colour we perceive on occasion of it."-- +FRENCH.] we yet know with far greater clearness its property of +figure than its colour. + + LXX. That we may judge of sensible things in two ways, by the one +of which we avoid error, by the other fall into it. + +It is thus manifest that to say we perceive colours in objects is in +reality equivalent to saying we perceive something in objects and +are yet ignorant of what it is, except as that which determines in +us a certain highly vivid and clear sensation, which we call the +sensation of colours. There is, however, very great diversity in the +manner of judging: for so long as we simply judge that there is an +unknown something in objects (that is, in things such as they are, +from which the sensation reached us), so far are we from falling +into error that, on the contrary, we thus rather provide against it, +for we are less apt to judge rashly of a thing which we observe we +do not know. But when we think we perceive colours in objects, +although we are in reality ignorant of what we then denominate +colour, and are unable to conceive any resemblance between the +colour we suppose to be in objects, and that of which we are +conscious in sensation, yet because we do not observe this, or +because there are in objects several properties, as size, figure, +number, etc., which, as we clearly know, exist, or may exist in them +as they are perceived by our senses or conceived by our +understanding, we easily glide into the error of holding that what +is called colour in objects is something entirely resembling the +colour we perceive, and thereafter of supposing that we have a clear +perception of what is in no way perceived by us. + + LXXI. That the chief cause of our errors is to be found in the +prejudices of our childhood. + +And here we may notice the first and chief cause of our errors. In +early life the mind was so closely bound to the body that it +attended to nothing beyond the thoughts by which it perceived the +objects that made impression on the body; nor as yet did it refer +these thoughts to anything existing beyond itself, but simply felt +pain when the body was hurt, or pleasure when anything beneficial to +the body occurred, or if the body was so highly affected that it was +neither greatly benefited nor hurt, the mind experienced the +sensations we call tastes, smells, sounds, heat, cold, light, +colours, and the like, which in truth are representative of nothing +existing out of our mind, and which vary according to the +diversities of the parts and modes in which the body is affected. +[Footnote: "which vary according to the diversities of the movements +that pass from all parts of our body to the part of the brain to +which it (the mind) is closely joined and united."--FRENCH.] The +mind at the same time also perceived magnitudes, figures, motions, +and the like, which were not presented to it as sensations but as +things or the modes of things existing, or at least capable of +existing out of thought, although it did not yet observe this +difference between these two kinds of perceptions. And afterwards +when the machine of the body, which has been so fabricated by nature +that it can of its own inherent power move itself in various ways, +by turning itself at random on every side, followed after what was +useful and avoided what was detrimental; the mind, which was closely +connected with it, reflecting on the objects it pursued or avoided, +remarked, for the first time, that they existed out of itself, and +not only attributed to them magnitudes, figures, motions, and the +like, which it apprehended either as things or as the modes of +things, but, in addition, attributed to them tastes, odours, and the +other ideas of that sort, the sensations of which were caused by +itself; [Footnote: "which it perceived on occasion of them" (i.e., +of external objects).--FRENCH.] and as it only considered other +objects in so far as they were useful to the body, in which it was +immersed, it judged that there was greater or less reality in each +object, according as the impressions it caused on the body were more +or less powerful. Hence arose the belief that there was more +substance or body in rocks and metals than in air or water, because +the mind perceived in them more hardness and weight. Moreover, the +air was thought to be merely nothing so long as we experienced no +agitation of it by the wind, or did not feel it hot or cold. And +because the stars gave hardly more light than the slender flames of +candles, we supposed that each star was but of this size. Again, +since the mind did not observe that the earth moved on its axis, or +that its superficies was curved like that of a globe, it was on that +account more ready to judge the earth immovable and its surface +flat. And our mind has been imbued from our infancy with a thousand +other prejudices of the same sort which afterwards in our youth we +forgot we had accepted without sufficient examination, and admitted +as possessed of the highest truth and clearness, as if they had been +known by means of our senses, or implanted in us by nature. + + LXXII. That the second cause of our errors is that we cannot forget +these prejudices. + +And although now in our mature years, when the mind, being no longer +wholly subject to the body, is not in the habit of referring all +things to it, but also seeks to discover the truth of things +considered in themselves, we observe the falsehood of a great many +of the judgments we had before formed; yet we experience a +difficulty in expunging them from our memory, and, so long as they +remain there, they give rise to various errors. Thus, for example, +since from our earliest years we imagined the stars to be of very +small size, we find it highly difficult to rid ourselves of this +imagination, although assured by plain astronomical reasons that +they are of the greatest,--so prevailing is the power of +preconceived opinion. + + LXXIII. The third cause is, that we become fatigued by attending to +those objects which are not present to the senses; and that we are +thus accustomed to judge of these not from present perception but +from pre-conceived opinion. + +Besides, our mind cannot attend to any object without at length +experiencing some pain and fatigue; and of all objects it has the +greatest difficulty in attending to those which are present neither +to the senses nor to the imagination: whether for the reason that +this is natural to it from its union with the body, or because in +our early years, being occupied merely with perceptions and +imaginations, it has become more familiar with, and acquired greater +facility in thinking in those modes than in any other. Hence it also +happens that many are unable to conceive any substance except what +is imaginable and corporeal, and even sensible. For they are +ignorant of the circumstance, that those objects alone are +imaginable which consist in extension, motion, and figure, while +there are many others besides these that are intelligible; and they +persuade themselves that nothing can subsist but body, and, finally, +that there is no body which is not sensible. And since in truth we +perceive no object such as it is by sense alone [but only by our +reason exercised upon sensible objects], as will hereafter be +clearly shown, it thus happens that the majority during life +perceive nothing unless in a confused way. + + LXXIV. The fourth source of our errors is, that we attach our +thoughts to words which do not express them with accuracy. + +Finally, since for the use of speech we attach all our conceptions +to words by which to express them, and commit to memory our thoughts +in connection with these terms, and as we afterwards find it more +easy to recall the words than the things signified by them, we can +scarcely conceive anything with such distinctness as to separate +entirely what we conceive from the words that were selected to +express it. On this account the majority attend to words rather than +to things; and thus very frequently assent to terms without +attaching to them any meaning, either because they think they once +understood them, or imagine they received them from others by whom +they were correctly understood. This, however, is not the place to +treat of this matter in detail, seeing the nature of the human body +has not yet been expounded, nor the existence even of body +established; enough, nevertheless, appears to have been said to +enable one to distinguish such of our conceptions as are clear and +distinct from those that are obscure and confused. + + LXXV. Summary of what must be observed in order to philosophize +correctly. + +Wherefore if we would philosophize in earnest, and give ourselves to +the search after all the truths we are capable of knowing, we must, +in the first place, lay aside our prejudices; in other words, we +must take care scrupulously to withhold our assent from the opinions +we have formerly admitted, until upon new examination we discover +that they are true. We must, in the next place, make an orderly +review of the notions we have in our minds, and hold as true all and +only those which we will clearly and distinctly apprehend. In this +way we will observe, first of all, that we exist in so far as it is +our nature to think, and at the same time that there is a God upon +whom we depend; and after considering his attributes we will be able +to investigate the truth of all other things, since God is the cause +of them. Besides the notions we have of God and of our mind, we will +likewise find that we possess the knowledge of many propositions +which are eternally true, as, for example, that nothing cannot be +the cause of anything, etc. We will farther discover in our minds +the knowledge of a corporeal or extended nature that may be moved, +divided, etc., and also of certain sensations that affect us, as of +pain, colours, tastes, etc., although we do not yet know the cause +of our being so affected; and, comparing what we have now learne'd, +by examining those things in their order, with our former confused +knowledge of them, we will acquire the habit of forming clear and +distinct conceptions of all the objects we are capable of knowing. +In these few precepts seem to me to be comprised the most general +and important principles of human knowledge. + + LXXVI. That we ought to prefer the Divine authority to our +perception; [Footnote: "reasonings."--FRENCH]. but that, apart from +things revealed, we ought to assent to nothing that we do not +clearly apprehend. + +Above all, we must impress on our memory the infallible rule, that +what God has revealed is incomparably more certain than anything +else; and that, we ought to submit our belief to the Divine +authority rather than to our own judgment, even although perhaps the +light of reason should, with the greatest clearness and evidence, +appear to suggest to us something contrary to what is revealed. But +in things regarding which there is no revelation, it is by no means +consistent with the character of a philosopher to accept as true +what he has not ascertained to be such, and to trust more to the +senses, in other words, to the inconsiderate judgments of childhood +than to the dictates of mature reason. + + PART II. + +OF THE PRINCIPLES OF MATERIAL THINGS. + +I. The grounds on which the existence of material things may be +known with certainty. + +Although we are all sufficiently persuaded of the existence of +material things, yet, since this was before called in question by +us, and since we reckoned the persuasion of their existence as among +the prejudices of our childhood, it is now necessary for us to +investigate the grounds on which this truth may be known with +certainty. In the first place, then, it cannot be doubted that every +perception we have comes to us from some object different from our +mind; for it is not in our power to cause ourselves to experience +one perception rather than another, the perception being entirely +dependent on the object which affects our senses. It may, indeed, be +matter of inquiry whether that object be God, or something different +from God; but because we perceive, or rather, stimulated by sense, +clearly and distinctly apprehend, certain matter extended in length, +breadth, and thickness, the various parts of which have different +figures and motions, and give rise to the sensation we have of +colours, smells, pain, etc., God would, without question, deserve to +be regarded as a deceiver, if he directly and of himself presented +to our mind the idea of this extended matter, or merely caused it to +be presented to us by some object which possessed neither extension, +figure, nor motion. For we clearly conceive this matter as entirely +distinct from God, and from ourselves, or our mind; and appear even +clearly to discern that the idea of it is formed in us on occasion +of objects existing out of our minds, to which it is in every +respect similar. But since God cannot deceive us, for this is +repugnant to his nature, as has been already remarked, we must +unhesitatingly conclude that there exists a certain object extended +in length, breadth, and thickness, and possessing all those +properties which we clearly apprehend to belong to what is extended. +And this extended substance is what we call body or matter. + + II. How we likewise know that the human body is closely connected +with the mind. + +We ought also to conclude that a certain body is more closely united +to our mind than any other, because we clearly observe that pain and +other sensations affect us without our foreseeing them; and these, +the mind is conscious, do not arise from itself alone, nor pertain +to it, in so far as it is a thing which thinks, but only in so far +as it is united to another thing extended and movable, which is +called the human body. But this is not the place to treat in detail +of this matter. + + III. That the perceptions of the senses do not teach us what is in +reality in things, but what is beneficial of hurtful to the +composite whole of mind and body. + +It will be sufficient to remark that the perceptions of the senses +are merely to be referred to this intimate union of the human body +and mind, and that they usually make us aware of what, in external +objects, may be useful or adverse to this union, but do not present +to us these objects as they are in themselves, unless occasionally +and by accident. For, after this observation, we will without +difficulty lay aside the prejudices of the senses, and will have +recourse to our understanding alone on this question by reflecting +carefully on the ideas implanted in it by nature. + + IV. That the nature of body consists not in weight hardness, colour +and the like, but in extension alone. + +In this way we will discern that the nature of matter or body, +considered in general, does not consist in its being hard, or +ponderous, or coloured, or that which affects our senses in any +other way, but simply in its being a substance extended in length, +breadth, and depth. For with respect to hardness, we know nothing of +it by sense farther than that the parts of hard bodies resist the +motion of our hands on coming into contact with them; but if every +time our hands moved towards any part, all the bodies in that place +receded as quickly as our hands approached, we should never feel +hardness; and yet we have no reason to believe that bodies which +might thus recede would on this account lose that which makes them +bodies. The nature of body does not, therefore, consist in hardness. +In the same way, it may be shown that weight, colour, and all the +other qualities of this sort, which are perceived in corporeal +matter, may be taken from it, itself meanwhile remaining entire: it +thus follows that the nature of body depends on none of these. + + V. That the truth regarding the nature of body is obscured by the +opinions respecting rarefaction and a vacuum with which we are pre- +occupied. + +There still remain two causes to prevent its being fully admitted +that the true nature of body consists in extension alone. The first +is the prevalent opinion, that most bodies admit of being so +rarefied and condensed that, when rarefied, they have greater +extension than when condensed; and some even have subtilized to such +a degree as to make a distinction between the substance of body and +its quantity, and between quantity itself and extension. The second +cause is this, that where we conceive only extension in length, +breadth, and depth, we are not in the habit of saying that body is +there, but only space and further void space, which the generality +believe to be a mere negation. + + VI. In what way rarefaction takes place. + +But with regard to rarefaction and condensation, whoever gives his +attention to his own thoughts, and admits nothing of which he is not +clearly conscious, will not suppose that there is anything in those +processes further than a change of figure in the body rarefied or +condensed: so that, in other words, rare bodies are those between +the parts of which there are numerous distances filled with other +bodies; and dense bodies, on the other hand, those whose parts +approaching each other, either diminish these distances or take them +wholly away, in the latter of which cases the body is rendered +absolutely dense. The body, however, when condensed, has not, +therefore, less extension than when the parts embrace a greater +space, owing to their removal from each other, and their dispersion +into branches. For we ought not to attribute to it the extension of +the pores or distances which its parts do not occupy when it is +rarefied, but to the other bodies that fill these interstices; just +as when we see a sponge full of water or any other liquid, we do not +suppose that each part of the sponge has on this account greater +extension than when compressed and dry, but only that its pores are +wider, and therefore that the body is diffused over a larger space. + + VII. That rarefaction cannot be intelligibly explained unless in +the way here proposed. + +And indeed I am unable to discover the force of the reasons which +have induced some to say that rarefaction is the result of the +augmentation of the quantity of body, rather than to explain it on +the principle exemplified in the case of a sponge. For although when +air or water is rarefied we do not see any of the pores that are +rendered large, or the new body that is added to occupy them, it is +yet less agreeable to reason to suppose something that is +unintelligible for the purpose of giving a verbal and merely +apparent explanation of the rarefaction of bodies, than to conclude, +because of their rarefaction, that there are pores or distances +between the parts which are increased in size, and filled with some +new body. Nor ought we to refrain from assenting to this +explanation, because we perceive this new body by none of our +senses, for there is no reason which obliges us to believe that we +should perceive by our senses all the bodies in existence. And we +see that it is very easy to explain rarefaction in this manner, but +impossible in any other; for, in fine, there would be, as appears to +me, a manifest contradiction in supposing that any body was +increased by a quantity or extension which it had not before, +without the addition to it of a new extended substance, in other +words, of another body, because it is impossible to conceive any +addition of extension or quantity to a thing without supposing the +addition of a substance having quantity or extension, as will more +clearly appear from what follows. + + VIII. That quantity and number differ only in thought (RATIONE) +from that which has quantity and is numbered. + +For quantity differs from extended substance, and number from what +is numbered, not in reality but merely in our thought; so that, for +example, we may consider the whole nature of a corporeal substance +which is comprised in a space of ten feet, although we do not attend +to this measure of ten feet, for the obvious reason that the thing +conceived is of the same nature in any part of that space as in the +whole; and, on the other hand, we can conceive the number ten, as +also a continuous quantity of ten feet, without thinking of this +determinate substance, because the concept of the number ten is +manifestly the same whether we consider a number of ten feet or ten +of anything else; and we can conceive a continuous quantity of ten +feet without thinking of this or that determinate substance, +although we cannot conceive it without some extended substance of +which it is the quantity. It is in reality, however, impossible that +any, even the least part, of such quantity or extension, can be +taken away, without the retrenchment at the same time of as much of +the substance, nor, on the other hand, can we lessen the substance, +without at the same time taking as much from the quantity or +extension. + + IX. That corporeal substance, when distinguished from its quantity, +is confusedly conceived as something incorporeal. + +Although perhaps some express themselves otherwise on this matter, I +am nevertheless convinced that they do not think differently from +what I have now said: for when they distinguish (corporeal) +substance from extension or quantity, they either mean nothing by +the word (corporeal) substance, or they form in their minds merely a +confused idea of incorporeal substance, which they falsely attribute +to corporeal, and leave to extension the true idea of this corporeal +substance; which extension they call an accident, but with such +impropriety as to make it easy to discover that their words are not +in harmony with their thoughts. + + X. What space or internal place is. + +Space or internal place, and the corporeal substance which is +comprised in it, are not different in reality, but merely in the +mode in which they are wont to be conceived by us. For, in truth, +the same extension in length, breadth, and depth, which constitutes +space, constitutes body; and the difference between them lies only +in this, that in body we consider extension as particular, and +conceive it to change with the body; whereas in space we attribute +to extension a generic unity, so that after taking from a certain +space the body which occupied it, we do not suppose that we have at +the same time removed the extension of the space, because it appears +to us that the same extension remains there so long as it is of the +same magnitude and figure, and preserves the same situation in +respect to certain bodies around it, by means of which we determine +this space. + + XI. How space is not in reality different from corporeal substance. + +And indeed it will be easy to discern that it is the same extension +which constitutes the nature of body as of space, and that these two +things are mutually diverse only as the nature of the genus and +species differs from that of the individual, provided we reflect on +the idea we have of any body, taking a stone for example, and reject +all that is not essential to the nature of body. In the first place, +then, hardness may be rejected, because if the stone were liquefied +or reduced to powder, it would no longer possess hardness, and yet +would not cease to be a body; colour also may be thrown out of +account, because we have frequently seen stones so transparent as to +have no colour; again, we may reject weight, because we have the +case of fire, which, though very light, is still a body; and, +finally, we may reject cold, heat, and all the other qualities of +this sort, either because they are not considered as in the stone, +or because, with the change of these qualities, the stone is not +supposed to have lost the nature of body. After this examination we +will find that nothing remains in the idea of body, except that it +is something extended in length, breadth, and depth; and this +something is comprised in our idea of space, not only of that which +is full of body, but even of what is called void space. + + XII. How space differs from body in our mode of conceiving it. + +There is, however, some difference between them in the mode of +conception; for if we remove a stone from the space or place in +which it was, we conceive that its extension also is taken away, +because we regard this as particular, and inseparable from the stone +itself: but meanwhile we suppose that the same extension of place in +which this stone was remains, although the place of the stone be +occupied by wood, water, air, or by any other body, or be even +supposed vacant, because we now consider extension in general, and +think that the same is common to stones, wood, water, air, and other +bodies, and even to a vacuum itself, if there is any such thing, +provided it be of the same magnitude and figure as before, and +preserve the same situation among the external bodies which +determine this space. + + XIII. What external place is. + +The reason of which is, that the words place and space signify +nothing really different from body which is said to be in place, but +merely designate its magnitude, figure, and situation among other +bodies. For it is necessary, in order to determine this situation, +to regard certain other bodies which we consider as immovable; and, +according as we look to different bodies, we may see that the same +thing at the same time does and does not change place. For example, +when a vessel is being carried out to sea, a person sitting at the +stern may be said to remain always in one place, if we look to the +parts of the vessel, since with respect to these he preserves the +same situation; and on the other hand, if regard be had to the +neighbouring shores, the same person will seem to be perpetually +changing place, seeing he is constantly receding from one shore and +approaching another. And besides, if we suppose that the earth +moves, and that it makes precisely as much way from west to east as +the vessel from east to west, we will again say that the person at +the stern does not change his place, because this place will be +determined by certain immovable points which we imagine to be in the +heavens. But if at length we are persuaded that there are no points +really immovable in the universe, as will hereafter be shown to be +probable, we will thence conclude that nothing has a permanent place +unless in so far as it is fixed by our thought. + + XIV. Wherein place and space differ. + +The terms place and space, however, differ in signification, because +place more expressly designates situation than magnitude or figure, +while, on the other hand, we think of the latter when we speak of +space. For we frequently say that a thing succeeds to the place of +another, although it be not exactly of the same magnitude or figure; +but we do not therefore admit that it occupies the same space as the +other; and when the situation is changed we say that the place also +is changed, although there are the same magnitude and figure as +before: so that when we say that a thing is in a particular place, +we mean merely that it is situated in a determinate way in respect +of certain other objects; and when we add that it occupies such a +space or place, we understand besides that it is of such determinate +magnitude and figure as exactly to fill this space. + + XV. How external place is rightly taken for the superficies of the +surrounding body. + +And thus we never indeed distinguish space from extension in length, +breadth, and depth; we sometimes, however, consider place as in the +thing placed, and at other times as out of it. Internal place indeed +differs in no way from space; but external place may be taken for +the superficies that immediately surrounds the thing placed. It +ought to be remarked that by superficies we do not here understand +any part of the surrounding body, but only the boundary between the +surrounding and surrounded bodies, which is nothing more than a +mode; or at least that we speak of superficies in general which is +no part of one body rather than another, but is always considered +the same, provided it retain the same magnitude and figure. For +although the whole surrounding body with its superficies were +changed, it would not be supposed that the body which was surrounded +by it had therefore changed its place, if it meanwhile preserved the +same situation with respect to the other bodies that are regarded as +immovable. Thus, if we suppose that a boat is carried in one +direction by the current of a stream, and impelled by the wind in +the opposite with an equal force, so that its situation with respect +to the banks is not changed, we will readily admit that it remains +in the same place, although the whole superficies which surrounds it +is incessantly changing. + + XVI. That a vacuum or space in which there is absolutely no body is +repugnant to reason. + +With regard to a vacuum, in the philosophical sense of the term, +that is, a space in which there is no substance, it is evident that +such does not exist, seeing the extension of space or internal place +is not different from that of body. For since from this alone, that +a body has extension in length, breadth, and depth, we have reason +to conclude that it is a substance, it being absolutely +contradictory that nothing should possess extension, we ought to +form a similar inference regarding the space which is supposed void, +viz., that since there is extension in it there is necessarily also +substance. + + XVII. That a vacuum in the ordinary use of the term does not +exclude all body. + +And, in truth, by the term vacuum in its common use, we do not mean +a place or space in which there is absolutely nothing, but only a +place in which there is none of those things we presume ought to be +there. Thus, because a pitcher is made to hold water, it is said to +be empty when it is merely filled with air; or if there are no fish +in a fish-pond, we say there is nothing in it, although it be full +of water; thus a vessel is said to be empty, when, in place of the +merchandise which it was designed to carry, it is loaded with sand +only, to enable it to resist the violence of the wind; and, finally, +it is in the same sense that we say space is void when it contains +nothing sensible, although it contain created and self-subsisting +matter; for we are not in the habit of considering the bodies near +us, unless in so far as they cause in our organs of sense, +impressions strong enough to enable us to perceive them. And if, in +place of keeping in mind what ought to be understood by these terms +a vacuum and nothing, we afterwards suppose that in the space we +called a vacuum, there is not only no sensible object, but no object +at all, we will fall into the same error as if, because a pitcher in +which there is nothing but air, is, in common speech, said to be +empty, we were therefore to judge that the air contained in it is +not a substance (RES SUBSISTENS). + + XVIII. How the prejudice of an absolute vacuum is to be corrected. + +We have almost all fallen into this error from the earliest age, +for, observing that there is no necessary connection between a +vessel and the body it contains, we thought that God at least could +take from a vessel the body which occupied it, without it being +necessary that any other should be put in the place of the one +removed. But that we may be able now to correct this false opinion, +it is necessary to remark that there is in truth no connection +between the vessel and the particular body which it contains, but +that there is an absolutely necessary connection between the concave +figure of the vessel and the extension considered generally which +must be comprised in this cavity; so that it is not more +contradictory to conceive a mountain without a valley than such a +cavity without the extension it contains, or this extension apart +from an extended substance, for, as we have often said, of nothing +there can be no extension. And accordingly, if it be asked what +would happen were God to remove from a vessel all the body contained +in it, without permitting another body to occupy its place, the +answer must be that the sides of the vessel would thus come into +proximity with each other. For two bodies must touch each other when +there is nothing between them, and it is manifestly contradictory +for two bodies to be apart, in other words, that there should be a +distance between them, and this distance yet be nothing; for all +distance is a mode of extension, and cannot therefore exist without +an extended substance. + + XIX. That this confirms what was said of rarefaction. + +After we have thus remarked that the nature of corporeal substance +consists only in its being an extended thing, and that its extension +is not different from that which we attribute to space, however +empty, it is easy to discover the impossibility of any one of its +parts in any way whatsoever occupying more space at one time than at +another, and thus of being otherwise rarefied than in the way +explained above; and it is easy to perceive also that there cannot +be more matter or body in a vessel when it is filled with lead or +gold, or any other body however heavy and hard, than when it but +contains air and is supposed to be empty: for the quantity of the +parts of which a body is composed does not depend on their weight or +hardness, but only on the extension, which is always equal in the +same vase. + + XX. That from this the non-existence of atoms may likewise be +demonstrated. + +We likewise discover that there cannot exist any atoms or parts of +matter that are of their own nature indivisible. For however small +we suppose these parts to be, yet because they are necessarily +extended, we are always able in thought to divide any one of them +into two or more smaller parts, and may accordingly admit their +divisibility. For there is nothing we can divide in thought which we +do not thereby recognize to be divisible; and, therefore, were we to +judge it indivisible our judgment would not be in harmony with the +knowledge we have of the thing; and although we should even suppose +that God had reduced any particle of matter to a smallness so +extreme that it did not admit of being further divided, it would +nevertheless be improperly styled indivisible, for though God had +rendered the particle so small that it was not in the power of any +creature to divide it, he could not however deprive himself of the +ability to do so, since it is absolutely impossible for him to +lessen his own omnipotence, as was before observed. Wherefore, +absolutely speaking, the smallest extended particle is always +divisible, since it is such of its very nature. + + XXI. It is thus also demonstrated that the extension of the world +is indefinite. + +We further discover that this world or the whole (universitas) of +corporeal substance, is extended without limit, for wherever we fix +a limit, we still not only imagine beyond it spaces indefinitely +extended, but perceive these to be truly imaginable, in other words, +to be in reality such as we imagine them; so that they contain in +them corporeal substance indefinitely extended, for, as has been +already shown at length, the idea of extension which we conceive in +any space whatever is plainly identical with the idea of corporeal +substance. + + XXII. It also follows that the matter of the heavens and earth is +the same, and that there cannot be a plurality of worlds. + +And it may also be easily inferred from all this that the earth and +heavens are made of the same matter; and that even although there +were an infinity of worlds, they would all be composed of this +matter; from which it follows that a plurality of worlds is +impossible, because we clearly conceive that the matter whose nature +consists only in its being an extended substance, already wholly +occupies all the imaginable spaces where these other worlds could +alone be, and we cannot find in ourselves the idea of any other +matter. + + XXIII. That all the variety of matter, or the diversity of its +forms, depends on motion. + +There is therefore but one kind of matter in the whole universe, and +this we know only by its being extended. All the properties we +distinctly perceive to belong to it are reducible to its capacity of +being divided and moved according to its parts; and accordingly it +is capable of all those affections which we perceive can arise from +the motion of its parts. For the partition of matter in thought +makes no change in it; but all variation of it, or diversity of +form, depends on motion. The philosophers even seem universally to +have observed this, for they said that nature was the principle of +motion and rest, and by nature they understood that by which all +corporeal things become such as they are found in experience. + + XXIV. What motion is, taking the term in its common use. + +But motion (viz., local, for I can conceive no other kind of motion, +and therefore I do not think we ought to suppose there is any other +in nature), in the ordinary sense of the term, is nothing more than +the action by which a body passes from one place to another. And +just as we have remarked above that the same thing may be said to +change and not to change place at the same time, so also we may say +that the same thing is at the same time moved and not moved. Thus, +for example, a person seated in a vessel which is setting sail, +thinks he is in motion if he look to the shore that he has left, and +consider it as fixed; but not if he regard the ship itself, among +the parts of which he preserves always the same situation. Moreover, +because we are accustomed to suppose that there is no motion without +action, and that in rest there is the cessation of action, the +person thus seated is more properly said to be at rest than in +motion, seeing he is not conscious of being in action. + + XXV. What motion is properly so called. + +But if, instead of occupying ourselves with that which has no +foundation, unless in ordinary usage, we desire to know what ought +to be understood by motion according to the truth of the thing, we +may say, in order to give it a determinate nature, that it is THE +TRANSPORTING OF ONE PART OF MATTER OR OF ONE BODY FROM THE VICINITY +OF THOSE BODIES THAT ARE IN IMMEDIATE CONTACT WITH IT, OR WHICH WE +REGARD AS AT REST, to the vicinity of other bodies. By a body as a +part of matter, I understand all that which is transferred together, +although it be perhaps composed of several parts, which in +themselves have other motions; and I say that it is the transporting +and not the force or action which transports, with the view of +showing that motion is always in the movable thing, not in that +which moves; for it seems to me that we are not accustomed to +distinguish these two things with sufficient accuracy. Farther, I +understand that it is a mode of the movable thing, and not a +substance, just as figure is a property of the thing figured, and +repose of that which is at rest. + + + +PART III. + +OF THE VISIBLE WORLD. + + I. That we cannot think too highly of the works of God. + +Having now ascertained certain principles of material things, which +were sought, not by the prejudices of the senses, but by the light +of reason, and which thus possess so great evidence that we cannot +doubt of their truth, it remains for us to consider whether from +these alone we can deduce the explication of all the phenomena of +nature. We will commence with those phenomena that are of the +greatest generality, and upon which the others depend, as, for +example, with the general structure of this whole visible world. But +in order to our philosophizing aright regarding this, two things are +first of all to be observed. The first is, that we should ever bear +in mind the infinity of the power and goodness of God, that we may +not fear falling into error by imagining his works to be too great, +beautiful, and perfect, but that we may, on the contrary, take care +lest, by supposing limits to them of which we have no certain +knowledge, we appear to think less highly than we ought of the power +of God. + + II. That we ought to beware lest, in our presumption, we imagine +that the ends which God proposed to himself in the creation of the +world are understood by us. + +The second is, that we should beware of presuming too highly of +ourselves, as it seems we should do if we supposed certain limits to +the world, without being assured of their existence either by +natural reasons or by divine revelation, as if the power of our +thought extended beyond what God has in reality made; but likewise +still more if we persuaded ourselves that all things were created by +God for us only, or if we merely supposed that we could comprehend +by the power of our intellect the ends which God proposed to himself +in creating the universe. + + III. In what sense it may be said that all things were created for +the sake of man. + +For although, as far as regards morals, it may be a pious thought to +believe that God made all things for us, seeing we may thus be +incited to greater gratitude and love toward him; and although it is +even in some sense true, because there is no created thing of which +we cannot make some use, if it be only that of exercising our mind +in considering it, and honouring God on account of it, it is yet by +no means probable that all things were created for us in this way +that God had no other end in their creation; and this supposition +would be plainly ridiculous and inept in physical reasoning, for we +do not doubt but that many things exist, or formerly existed and +have now ceased to be, which were never seen or known by man, and +were never of use to him. + + + +PART IV. + +OF THE EARTH. + + CLXXXVIII. Of what is to be borrowed from disquisitions on animals +and man to advance the knowledge of material objects. + +I should add nothing farther to this the Fourth Part of the +Principles of Philosophy, did I purpose carrying out my original +design of writing a Fifth and Sixth Part, the one treating of things +possessed of life, that is, animals and plants, and the other of +man. But because I have not yet acquired sufficient knowledge of all +the matters of which I should desire to treat in these two last +parts, and do not know whether I shall ever have sufficient leisure +to finish them, I will here subjoin a few things regarding the +objects of our senses, that I may not, for the sake of the latter, +delay too long the publication of the former parts, or of what may +be desiderated in them, which I might have reserved for explanation +in those others: for I have hitherto described this earth, and +generally the whole visible world, as if it were merely a machine in +which there was nothing at all to consider except the figures and +motions of its parts, whereas our senses present to us many other +things, for example colours, smells, sounds, and the like, of which, +if I did not speak at all, it would be thought I had omitted the +explication of the majority of the objects that are in nature. + + CLXXXIX. What perception (SENSUS) is, and how we perceive. + +We must know, therefore, that although the human soul is united to +the whole body, it has, nevertheless, its principal seat in the +brain, where alone it not only understands and imagines, but also +perceives; and this by the medium of the nerves, which are extended +like threads from the brain to all the other members, with which +they are so connected that we can hardly touch any one of them +without moving the extremities of some of the nerves spread over it; +and this motion passes to the other extremities of those nerves +which are collected in the brain round the seat of the soul, +[Footnote: *** FOOTNOTE NOT VISIBLE IN PAGE IMAGE (#98, Text p 195)] +as I have already explained with sufficient minuteness in the fourth +chapter of the Dioptrics. But the movements which are thus excited +in the brain by the nerves variously affect the soul or mind, which +is intimately conjoined with the brain, according to the diversity +of the motions themselves. And the diverse affections of the mind or +thoughts that immediately arise from these motions, are called +perceptions of the senses (SENSUUM PERCEPTIONES), or, as we commonly +speak, sensations (SENSUS). + + CXC. Of the distinction of the senses; and, first, of the internal, +that is, of the affections of the mind (passions), and the natural +appetites. + +The varieties of these sensations depend, firstly, on the diversity +of the nerves themselves, and, secondly, of the movements that are +made in each nerve. We have not, however, as many different senses +as there are nerves. We can distinguish but seven principal classes +of nerves, of which two belong to the internal, and the other five +to the external senses. The nerves which extend to the stomach, the +oesophagus, the fauces, and the other internal parts that are +subservient to our natural wants, constitute one of our internal +senses. This is called the natural appetite (APPETITUS NATURALIS). +The other internal sense, which embraces all the emotions +(COMMOTIONES) of the mind or passions, and affections, as joy, +sadness, love, hate, and the like, depends upon the nerves which +extend to the heart and the parts about the heart, and are +exceedingly small; for, by way of example, when the blood happens to +be pure and well tempered, so that it dilates in the heart more +readily and strongly than usual, this so enlarges and moves the +small nerves scattered around the orifices, that there is thence a +corresponding movement in the brain, which affects the mind with a +certain natural feeling of joy; and as often as these same nerves +are moved in the same way, although this is by other causes, they +excite in our mind the same feeling (sensus, sentiment). Thus, the +imagination of the enjoyment of a good does not contain in itself +the feeling of joy, but it causes the animal spirits to pass from +the brain to the muscles in which these nerves are inserted; and +thus dilating the orifices of the heart, it also causes these small +nerves to move in the way appointed by nature to afford the +sensation of joy. Thus, when we receive news, the mind first of all +judges of it, and if the news be good, it rejoices with that +intellectual joy (GAUDIUM INTELLECTUALE) which is independent of any +emotion (COMMOTIO) of the body, and which the Stoics did not deny to +their wise man [although they supposed him exempt from all passion]. +But as soon as this joy passes from the understanding to the +imagination, the spirits flow from the brain to the muscles that are +about the heart, and there excite the motion of the small nerves, by +means of which another motion is caused in the brain, which affects +the mind with the sensation of animal joy (LAETITIA ANIMALIS). On +the same principle, when the blood is so thick that it flows but +sparingly into the ventricles of the heart, and is not there +sufficiently dilated, it excites in the same nerves a motion quite +different from the preceding, which, communicated to the brain, +gives to the mind the sensation of sadness, although the mind itself +is perhaps ignorant of the cause of its sadness. And all the other +causes which move these nerves in the same way may also give to the +mind the same sensation. But the other movements of the same nerves +produce other effects, as the feelings of love, hate, fear, anger, +etc., as far as they are merely affections or passions of the mind; +in other words, as far as they are confused thoughts which the mind +has not from itself alone, but from its being closely joined to the +body, from which it receives impressions; for there is the widest +difference between these passions and the distinct thoughts which we +have of what ought to be loved, or chosen, or shunned, etc., +[although these are often enough found together]. The natural +appetites, as hunger, thirst, and the others, are likewise +sensations excited in the mind by means of the nerves of the +stomach, fauces, and other parts, and are entirely different from +the will which we have to eat, drink, [and to do all that which we +think proper for the conservation of our body]; but, because this +will or appetition almost always accompanies them, they are +therefore named appetites. + + CXCI. Of the external senses; and first of touch. + +We commonly reckon the external senses five in number, because there +are as many different kinds of objects which move the nerves and +their organs, and an equal number of kinds of confused thoughts +excited in the soul by these emotions. In the first place, the +nerves terminating in the skin of the whole body can be touched +through this medium by any terrene objects whatever, and moved by +these wholes, in one way by their hardness, in another by their +gravity, in a third by their heat, in a fourth by their humidity, +etc.--and in as many diverse modes as they are either moved or +hindered from their ordinary motion, to that extent are diverse +sensations excited in the mind, from which a corresponding number of +tactile qualities derive their appellations. Besides this, when +these nerves are moved a little more powerfully than usual, but not +nevertheless to the degree by which our body is in any way hurt, +there thus arises a sensation of titillation, which is naturally +agreeable to the mind, because it testifies to it of the powers of +the body with which it is joined, [in that the latter can suffer the +action causing this titillation, without being hurt]. But if this +action be strong enough to hurt our body in any way, this gives to +our mind the sensation of pain. And we thus see why corporeal +pleasure and pain, although sensations of quite an opposite +character, arise nevertheless from causes nearly alike. + + CXCII. Of taste. + +In the second place, the other nerves scattered over the tongue and +the parts in its vicinity are diversely moved by the particles of +the same bodies, separated from each other and floating in the +saliva in the mouth, and thus cause sensations of diverse tastes +according to the diversity of figure in these particles. [Footnote: +In the French this section begins, "Taste, after touch the grossest +of the senses," etc.] + + CXCIII. Of smell. + +Thirdly, two nerves also or appendages of the brain, for they do not +go beyond the limits of the skull, are moved by the particles of +terrestrial bodies, separated and flying in the air, not indeed by +all particles indifferently, but by those only that are sufficiently +subtle and penetrating to enter the pores of the bone we call the +spongy, when drawn into the nostrils, and thus to reach the nerves. +From the different motions of these particles arise the sensations +of the different smells. + + CXCIV. Of hearing. + +Fourthly, there are two nerves within the ears, so attached to three +small bones that are mutually sustaining, and the first of which +rests on the small membrane that covers the cavity we call the +tympanum of the ear, that all the diverse vibrations which the +surrounding air communicates to this membrane are transmitted to the +mind by these nerves, and these vibrations give rise, according to +their diversity, to the sensations of the different sounds. + + CXCV. Of sight. + +Finally, the extremities of the optic nerves, composing the coat in +the eyes called the retina, are not moved by the air nor by any +terrestrial object, but only by the globules of the second element, +whence we have the sense of light and colours: as I have already at +sufficient length explained in the Dioptrics and treatise of +Meteors. [Footnote: In the French this section begins, "Finally, +sight is the most subtle of all the senses," etc.] + + CXCVI. That the soul perceives only in so far as it is in the +brain. + +It is clearly established, however, that the soul does not perceive +in so far as it is in each member of the body, but only in so far as +it is in the brain, where the nerves by their movements convey to it +the diverse actions of the external objects that touch the parts of +the body in which they are inserted. For, in the first place, there +are various maladies, which, though they affect the brain alone, yet +bring disorder upon, or deprive us altogether of the use of, our +senses, just as sleep, which affects the brain only, and yet takes +from us daily during a great part of our time the faculty of +perception, which afterwards in our waking state is restored to us. +The second proof is, that though there be no disease in the brain, +[or in the members in which the organs of the external senses are], +it is nevertheless sufficient to take away sensation from the part +of the body where the nerves terminate, if only the movement of one +of the nerves that extend from the brain to these members be +obstructed in any part of the distance that is between the two. And +the last proof is, that we sometimes feel pain as if in certain of +our members, the cause of which, however, is not in these members +where it is felt, but somewhere nearer the brain, through which the +nerves pass that give to the mind the sensation of it. I could +establish this fact by innumerable experiments; I will here, +however, merely refer to one of them. A girl suffering from a bad +ulcer in the hand, had her eyes bandaged whenever the surgeon came +to visit her, not being able to bear the sight of the dressing of +the sore; and, the gangrene having spread, after the expiry of a few +days the arm was amputated from the elbow [without the girl's +knowledge]; linen cloths tied one above the other were substituted +in place of the part amputated, so that she remained for some time +without knowing that the operation had been performed, and meanwhile +she complained of feeling various pains, sometimes in one finger of +the hand that was cut off, and sometimes in another. The only +explanation of this is, that the nerves which before stretched +downwards from the brain to the hand, and then terminated in the arm +close to the elbow, were there moved in the same way as they +required to be moved before in the hand for the purpose of +impressing on the mind residing in the brain the sensation of pain +in this or that finger. [And this clearly shows that the pain of the +hand is not felt by the mind in so far as it is in the hand, but in +so far as it is in the brain.] + + CXCVII. That the nature of the mind is such that from the motion +alone of body the various sensations can be excited in it. + +In the next place, it can be proved that our mind is of such a +nature that the motions of the body alone are sufficient to excite +in it all sorts of thoughts, without it being necessary that these +should in any way resemble the motions which give rise to them, and +especially that these motions can excite in it those confused +thoughts called sensations (SENSUS, SENSATIONES). For we see that +words, whether uttered by the voice or merely written, excite in our +minds all kinds of thoughts and emotions. On the same paper, with +the same pen and ink, by merely moving the point of the pen over the +paper in a particular way, we can trace letters that will raise in +the minds of our readers the thoughts of combats, tempests, or the +furies, and the passions of indignation and sorrow; in place of +which, if the pen be moved in another way hardly different from the +former, this slight change will cause thoughts widely different from +the above, such as those of repose, peace, pleasantness, and the +quite opposite passions of love and joy. Some one will perhaps +object that writing and speech do not immediately excite in the mind +any passions, or imaginations of things different from the letters +and sounds, but afford simply the knowledge of these, on occasion of +which the mind, understanding the signification of the words, +afterwards excites in itself the imaginations and passions that +correspond to the words. But what will be said of the sensations of +pain and titillation? The motion merely of a sword cutting a part of +our skin causes pain, [but does not on that account make us aware of +the motion or figure of the sword]. And it is certain that this +sensation of pain is not less different from the motion that causes +it, or from that of the part of our body which the sword cuts, than +are the sensations we have of colour, sound, odour, or taste. On +this ground we may conclude that our mind is of such a nature that +the motions alone of certain bodies can also easily excite in it all +the other sensations, as the motion of a sword excites in it the +sensation of pain. + + CXCVIII. That by our senses we know nothing of external objects +beyond their figure [or situation], magnitude, and motion. + +Besides, we observe no such difference between the nerves as to lead +us to judge that one set of them convey to the brain from the organs +of the external senses anything different from another, or that +anything at all reaches the brain besides the local motion of the +nerves themselves. And we see that local motion alone causes in us +not only the sensation of titillation and of pain, but also of light +and sounds. For if we receive a blow on the eye of sufficient force +to cause the vibration of the stroke to reach the retina, we see +numerous sparks of fire, which, nevertheless, are not out of our +eye; and when we stop our ear with our finger, we hear a humming +sound, the cause of which can only proceed from the agitation of the +air that is shut up within it. Finally, we frequently observe that +heat [hardness, weight], and the other sensible qualities, as far as +they are in objects, and also the forms of those bodies that are +purely material, as, for example, the forms of fire, are produced in +them by the motion of certain other bodies, and that these in their +turn likewise produce other motions in other bodies. And we can +easily conceive how the motion of one body may be caused by that of +another, and diversified by the size, figure, and situation of its +parts, but we are wholly unable to conceive how these same things +(viz., size, figure, and motion), can produce something else of a +nature entirely different from themselves, as, for example, those +substantial forms and real qualities which many philosophers suppose +to be in bodies; nor likewise can we conceive how these qualities or +forms possess force to cause motions in other bodies. But since we +know, from the nature of our soul, that the diverse motions of body +are sufficient to produce in it all the sensations which it has, and +since we learn from experience that several of its sensations are in +reality caused by such motions, while we do not discover that +anything besides these motions ever passes from the organs of the +external senses to the brain, we have reason to conclude that we in +no way likewise apprehend that in external objects, which we call +light, colour, smell, taste, sound, heat or cold, and the other +tactile qualities, or that which we call their substantial forms, +unless as the various dispositions of these objects which have the +power of moving our nerves in various ways. [Footnote: "the diverse +figures, situations, magnitudes, and motions of their parts."-- +French.] + + CXCIX. That there is no phenomenon of nature whose explanation has +been omitted in this treatise. + +And thus it may be gathered, from an enumeration that is easily +made, that there is no phenomenon of nature whose explanation has +been omitted in this treatise; for beyond what is perceived by the +senses, there is nothing that can be considered a phenomenon of +nature. But leaving out of account motion, magnitude, figure, [and +the situation of the parts of each body], which I have explained as +they exist in body, we perceive nothing out of us by our senses +except light, colours, smells, tastes, sounds, and the tactile +qualities; and these I have recently shown to be nothing more, at +least so far as they are known to us, than certain dispositions of +the objects, consisting in magnitude, figure, and motion. + + CC. That this treatise contains no principles which are not +universally received; and that this philosophy is not new, but of +all others the most ancient and common. + +But I am desirous also that it should be observed that, though I +have here endeavoured to give an explanation of the whole nature of +material things, I have nevertheless made use of no principle which +was not received and approved by Aristotle, and by the other +philosophers of all ages; so that this philosophy, so far from being +new, is of all others the most ancient and common: for I have in +truth merely considered the figure, motion, and magnitude of bodies, +and examined what must follow from their mutual concourse on the +principles of mechanics, which are confirmed by certain and daily +experience. But no one ever doubted that bodies are moved, and that +they are of various sizes and figures, according to the diversity of +which their motions also vary, and that from mutual collision those +somewhat greater than others are divided into many smaller, and thus +change figure. We have experience of the truth of this, not merely +by a single sense, but by several, as touch, sight, and hearing: we +also distinctly imagine and understand it. This cannot be said of +any of the other things that fall under our senses, as colours, +sounds, and the like; for each of these affects but one of our +senses, and merely impresses upon our imagination a confused image +of itself, affording our understanding no distinct knowledge of what +it is. + + CCI. That sensible bodies are composed of insensible particles. + +But I allow many particles in each body that are perceived by none +of our senses, and this will not perhaps be approved of by those who +take the senses for the measure of the knowable. [We greatly wrong +human reason, however, as appears to me, if we suppose that it does +not go beyond the eye-sight]; for no one can doubt that there are +bodies so small as not to be perceptible by any of our senses, +provided he only consider what is each moment added to those bodies +that are being increased little by little, and what is taken from +those that are diminished in the same way. A tree increases daily, +and it is impossible to conceive how it becomes greater than it was +before, unless we at the same time conceive that some body is added +to it. But who ever observed by the senses those small bodies that +are in one day added to a tree while growing? Among the philosophers +at least, those who hold that quantity is indefinitely divisible, +ought to admit that in the division the parts may become so small as +to be wholly imperceptible. And indeed it ought not to be a matter +of surprise, that we are unable to perceive very minute bodies; for +the nerves that must be moved by objects to cause perception are not +themselves very minute, but are like small cords, being composed of +a quantity of smaller fibres, and thus the most minute bodies are +not capable of moving them. Nor do I think that any one who makes +use of his reason will deny that we philosophize with much greater +truth when we judge of what takes place in those small bodies which +are imperceptible from their minuteness only, after the analogy of +what we see occurring in those we do perceive, [and in this way +explain all that is in nature, as I have essayed to do in this +treatise], than when we give an explanation of the same things by +inventing I know not what novelties, that have no relation to the +things we actually perceive, [as first matter, substantial forms, +and all that grand array of qualities which many are in the habit of +supposing, each of which is more difficult to comprehend than all +that is professed to be explained by means of them]. + + CCII. That the philosophy of Democritus is not less different from +ours than from the common. [Footnote: "that of Aristotle or the +others."--French.] + +But it may be said that Democritus also supposed certain corpuscles +that were of various figures, sizes, and motions, from the heaping +together and mutual concourse of which all sensible bodies arose; +and, nevertheless, his mode of philosophizing is commonly rejected +by all. To this I reply that the philosophy of Democritus was never +rejected by any one, because he allowed the existence of bodies +smaller than those we perceive, and attributed to them diverse +sizes, figures, and motions, for no one can doubt that there are in +reality such, as we have already shown; but it was rejected, in the +first place, because he supposed that these corpuscles were +indivisible, on which ground I also reject it; in the second place, +because he imagined there was a vacuum about them, which I show to +be impossible; thirdly, because he attributed gravity to these +bodies, of which I deny the existence in any body, in so far as a +body is considered by itself, because it is a quality that depends +on the relations of situation and motion which several bodies bear +to each other; and, finally, because he has not explained in +particular how all things arose from the concourse of corpuscles +alone, or, if he gave this explanation with regard to a few of them, +his whole reasoning was far from being coherent, [or such as would +warrant us in extending the same explanation to the whole of +nature]. This, at least, is the verdict we must give regarding his +philosophy, if we may judge of his opinions from what has been +handed down to us in writing. I leave it to others to determine +whether the philosophy I profess possesses a valid coherency, [and +whether on its principles we can make the requisite number of +deductions; and, inasmuch as the consideration of figure, magnitude, +and motion has been admitted by Aristotle and by all the others, as +well as by Democritus, and since I reject all that the latter has +supposed, with this single exception, while I reject generally all +that has been supposed by the others, it is plain that this mode of +philosophizing has no more affinity with that of Democritus than of +any other particular sect]. + + CCIII. How we may arrive at the knowledge of the figures, +[magnitudes], and motions of the insensible particles of bodies. + +But, since I assign determinate figures, magnitudes, and motions to +the insensible particles of bodies, as if I had seen them, whereas I +admit that they do not fall under the senses, some one will perhaps +demand how I have come by my knowledge of them. [To this I reply, +that I first considered in general all the clear and distinct +notions of material things that are to be found in our +understanding, and that, finding no others except those of figures, +magnitudes, and motions, and of the rules according to which these +three things can be diversified by each other, which rules are the +principles of geometry and mechanics, I judged that all the +knowledge man can have of nature must of necessity be drawn from +this source; because all the other notions we have of sensible +things, as confused and obscure, can be of no avail in affording us +the knowledge of anything out of ourselves, but must serve rather to +impede it]. Thereupon, taking as my ground of inference the simplest +and best known of the principles that have been implanted in our +minds by nature, I considered the chief differences that could +possibly subsist between the magnitudes, and figures, and situations +of bodies insensible on account of their smallness alone, and what +sensible effects could be produced by their various modes of coming +into contact; and afterwards, when I found like effects in the +bodies that we perceive by our senses, I judged that they could have +been thus produced, especially since no other mode of explaining +them could be devised. And in this matter the example of several +bodies made by art was of great service to me: for I recognize no +difference between these and natural bodies beyond this, that the +effects of machines depend for the most part on the agency of +certain instruments, which, as they must bear some proportion to the +hands of those who make them, are always so large that their figures +and motions can be seen; in place of which, the effects of natural +bodies almost always depend upon certain organs so minute as to +escape our senses. And it is certain that all the rules of mechanics +belong also to physics, of which it is a part or species, [so that +all that is artificial is withal natural]: for it is not less +natural for a clock, made of the requisite number of wheels, to mark +the hours, than for a tree, which has sprung from this or that seed, +to produce the fruit peculiar to it. Accordingly, just as those who +are familiar with automata, when they are informed of the use of a +machine, and see some of its parts, easily infer from these the way +in which the others, that are not seen by them, are made; so from +considering the sensible effects and parts of natural bodies, I have +essayed to determine the character of their causes and insensible +parts. + + CCIV. That, touching the things which our senses do not perceive, +it is sufficient to explain how they can be, [and that this is all +that Aristotle has essayed]. + +But here some one will perhaps reply, that although I have supposed +causes which could produce all natural objects, we ought not on this +account to conclude that they were produced by these causes; for, +just as the same artisan can make two clocks, which, though they +both equally well indicate the time, and are not different in +outward appearance, have nevertheless nothing resembling in the +composition of their wheels; so doubtless the Supreme Maker of +things has an infinity of diverse means at his disposal, by each of +which he could have made all the things of this world to appear as +we see them, without it being possible for the human mind to know +which of all these means he chose to employ. I most freely concede +this; and I believe that I have done all that was required, if the +causes I have assigned are such that their effects accurately +correspond to all the phenomena of nature, without determining +whether it is by these or by others that they are actually produced. +And it will be sufficient for the use of life to know the causes +thus imagined, for medicine, mechanics, and in general all the arts +to which the knowledge of physics is of service, have for their end +only those effects that are sensible, and that are accordingly to be +reckoned among the phenomena of nature. [Footnote: "have for their +end only to apply certain sensible bodies to each other in such a +way that, in the course of natural causes, certain sensible effects +may be produced; and we will be able to accomplish this quite as +well by considering the series of certain causes thus imagined, +although false, as if they were the true, since this series is +supposed similar as far as regards sensible effects."-French.] + +And lest it should be supposed that Aristotle did, or professed to +do, anything more than this, it ought to be remembered that he +himself expressly says, at the commencement of the seventh chapter +of the first book of the Meteorologies, that, with regard to things +which are not manifest to the senses, he thinks to adduce sufficient +reasons and demonstrations of them, if he only shows that they may +be such as he explains them. [Footnote: words in Greek] + + CCV. That nevertheless there is a moral certainty that all the +things of this world are such as has been here shown they may be. + +But nevertheless, that I may not wrong the truth by supposing it +less certain than it is, I will here distinguish two kinds of +certitude. The first is called moral, that is, a certainty +sufficient for the conduct of life, though, if we look to the +absolute power of God, what is morally certain may be false. [Thus, +those who never visited Rome do not doubt that it is a city of +Italy, though it might be that all from whom they got their +information were deceived]. Again, if any one, wishing to decipher a +letter written in Latin characters that are not placed in regular +order, bethinks himself of reading a B wherever an A is found, and a +C wherever there is a B, and thus of substituting in place of each +letter the one which follows it in the order of the alphabet, and if +by this means he finds that there are certain Latin words composed +of these, he will not doubt that the true meaning of the writing is +contained in these words, although he may discover this only by +conjecture, and although it is possible that the writer of it did +not arrange the letters on this principle of alphabetical order, but +on some other, and thus concealed another meaning in it: for this is +so improbable [especially when the cipher contains a number of +words] as to seem incredible. But they who observe how many things +regarding the magnet, fire, and the fabric of the whole world, are +here deduced from a very small number of principles, though they +deemed that I had taken them up at random and without grounds, will +yet perhaps acknowledge that it could hardly happen that so many +things should cohere if these principles were false. + + CCVI. That we possess even more than a moral certainty of it. + +Besides, there are some, even among natural, things which we judge +to be absolutely certain. [Absolute certainty arises when we judge +that it is impossible a thing can be otherwise than as we think it]. +This certainty is founded on the metaphysical ground, that, as God +is supremely good and the source of all truth, the faculty of +distinguishing truth from error which he gave us, cannot be +fallacious so long as we use it aright, and distinctly perceive +anything by it. Of this character are the demonstrations of +mathematics, the knowledge that material things exist, and the clear +reasonings that are formed regarding them. The results I have given +in this treatise will perhaps be admitted to a place in the class of +truths that are absolutely certain, if it be considered that they +are deduced in a continuous series from the first and most +elementary principles of human knowledge; especially if it be +sufficiently understood that we can perceive no external objects +unless some local motion be caused by them in our nerves, and that +such motion cannot be caused by the fixed stars, owing to their +great distance from us, unless a motion be also produced in them and +in the whole heavens lying between them and us: for these points +being admitted, all the others, at least the more general doctrines +which I have advanced regarding the world or earth [e. g., the +fluidity of the heavens, Part III., Section XLVI.], will appear to +be almost the only possible explanations of the phenomena they +present. + + CCVII. That, however, I submit all my opinions to the authority of +the church. + +Nevertheless, lest I should presume too far, I affirm nothing, but +submit all these my opinions to the authority of the church and the +judgment of the more sage; and I desire no one to believe anything I +may have said, unless he is constrained to admit it by the force and +evidence of reason. + + + + + +End of Project Gutenberg's The Principles of Philosophy, by Rene Descartes + diff --git a/old/4391.zip b/old/4391.zip Binary files differnew file mode 100644 index 0000000..aecfc50 --- /dev/null +++ b/old/4391.zip |