I am in doubt as to the propriety of making my first meditations in the place above mentioned matter of discourse; for these are so metaphysical, and so uncommon, as not, perhaps, to be acceptable to every one. And yet, that it may be determined whether the foundations that I have laid are sufficiently secure, I find myself in a measure constrained to advert to them. I had long before remarked that, in relation to practice, it is sometimes necessary to adopt, as if above doubt, opinions which we discern to be highly uncertain, as has been already said; but as I then desired to give my attention solely to the search after truth, I thought that a procedure exactly the opposite was called for, and that I ought to reject as absolutely false all opinions in regard to which I could suppose the least ground for doubt, in order to ascertain whether after that there remained aught in my belief that was wholly indubitable. Accordingly, seeing that our senses sometimes deceive us, I was willing to suppose that there existed nothing really such as they presented to us; and because some men err in reasoning, and fall into paralogisms, even on the simplest matters of geometry, I, convinced that I was as open to error as any other, rejected as false all the reasonings I had hitherto taken for demonstrations; and finally, when I considered that the very same thoughts (presentations) which we experience when awake may also be experienced when we are asleep, while there is at that time not one of them true, I supposed that all the objects (presentations) that had ever entered into my mind when awake, had in them no more truth than the illusions of my dreams. But immediately upon this I observed that, whilst I thus wished to think that all was false, it was absolutely necessary that I, who thus thought, should be somewhat; and as I observed that this truth, I think, therefore I am (COGITO ERGO SUM), was so certain and of such evidence that no ground of doubt, however extravagant, could be alleged by the sceptics capable of shaking it, I concluded that I might, without scruple, accept it as the first principle of the philosophy of which I was in search.
I am unsure whether I should discuss my first meditations in the place mentioned above. These reflections are so metaphysical and unusual that perhaps not everyone will welcome them. Yet I feel somewhat compelled to discuss them so that readers can judge whether my foundations are secure enough. As I said earlier, I had long noticed that practical decisions sometimes require us to treat highly uncertain opinions as beyond doubt. But at that time, I wanted to focus only on the search for truth. So I thought I needed to take exactly the opposite approach. I ought to reject as absolutely false every opinion about which I could imagine the slightest reason for doubt. My aim was to discover whether any belief remained that was entirely beyond doubt. Since our senses sometimes deceive us, I was willing to suppose that nothing really existed as our senses presented it. Some people also make mistakes in reasoning and draw faulty conclusions, even about the simplest matters of geometry. Because I believed I was as prone to error as anyone else, I rejected all my previous proofs as false. Finally, I considered that the very same thoughts (mental images) we experience while awake may also occur while we sleep. Yet while we sleep, not one of those thoughts is true. So I supposed that everything ever presented to my waking mind contained no more truth than the illusions of my dreams. But immediately I noticed that, while I tried to think everything was false, I, who was thinking, necessarily had to exist. I also saw that the truth I think, therefore I am (COGITO ERGO SUM) was completely certain and self-evident. No reason for doubt offered by the sceptics, however extreme, could shake it. So I concluded that I could accept this truth without hesitation as the first principle of the philosophy I sought.
In the next place, I attentively examined what I was and as I observed that I could suppose that I had no body, and that there was no world nor any place in which I might be; but that I could not therefore suppose that I was not; and that, on the contrary, from the very circumstance that I thought to doubt of the truth of other things, it most clearly and certainly followed that I was; while, on the other hand, if I had only ceased to think, although all the other objects which I had ever imagined had been in reality existent, I would have had no reason to believe that I existed; I thence concluded that I was a substance whose whole essence or nature consists only in thinking, and which, that it may exist, has need of no place, nor is dependent on any material thing; so that “I,” that is to say, the mind by which I am what I am, is wholly distinct from the body, and is even more easily known than the latter, and is such, that although the latter were not, it would still continue to be all that it is.
Next, I carefully examined what I was. I saw that I could suppose I had no body. I could also suppose there was no world and no place where I could be. But I could not therefore suppose that I did not exist. On the contrary, my very act of doubting the truth of other things showed most clearly and certainly that I existed. On the other hand, if I had simply stopped thinking, I would have had no reason to believe I existed. This would hold even if all the other things I had ever imagined really existed. I therefore concluded that I was a substance whose entire essence or nature consists only in thinking. To exist, this substance needs no place and depends on no material thing. So “I,” meaning the mind that makes me what I am, is entirely distinct from the body. The mind is even easier to know than the body. And even if the body did not exist, the mind would still remain all that it is.
After this I inquired in general into what is essential to the truth and certainty of a proposition; for since I had discovered one which I knew to be true, I thought that I must likewise be able to discover the ground of this certitude. And as I observed that in the words I think, therefore I am, there is nothing at all which gives me assurance of their truth beyond this, that I see very clearly that in order to think it is necessary to exist, I concluded that I might take, as a general rule, the principle, that all the things which we very clearly and distinctly conceive are true, only observing, however, that there is some difficulty in rightly determining the objects which we distinctly conceive.
After this, I asked what makes a statement true and certain. Since I had found one statement I knew was true, I thought I must also be able to discover why it was certain. I considered the words I think, therefore I am. I saw that my certainty about their truth rested entirely on one thing: I saw very clearly that thinking requires existence. So I concluded that I could adopt a general rule: all things we understand very clearly and distinctly are true. However, I noted that there is some difficulty in correctly determining what we understand distinctly.
In the next place, from reflecting on the circumstance that I doubted, and that consequently my being was not wholly perfect (for I clearly saw that it was a greater perfection to know than to doubt), I was led to inquire whence I had learned to think of something more perfect than myself; and I clearly recognized that I must hold this notion from some nature which in reality was more perfect. As for the thoughts of many other objects external to me, as of the sky, the earth, light, heat, and a thousand more, I was less at a loss to know whence these came; for since I remarked in them nothing which seemed to render them superior to myself, I could believe that, if these were true, they were dependencies on my own nature, in so far as it possessed a certain perfection, and, if they were false, that I held them from nothing, that is to say, that they were in me because of a certain imperfection of my nature. But this could not be the case with-the idea of a nature more perfect than myself; for to receive it from nothing was a thing manifestly impossible; and, because it is not less repugnant that the more perfect should be an effect of, and dependence on the less perfect, than that something should proceed from nothing, it was equally impossible that I could hold it from myself: accordingly, it but remained that it had been placed in me by a nature which was in reality more perfect than mine, and which even possessed within itself all the perfections of which I could form any idea; that is to say, in a single word, which was God. And to this I added that, since I knew some perfections which I did not possess, I was not the only being in existence (I will here, with your permission, freely use the terms of the schools); but, on the contrary, that there was of necessity some other more perfect Being upon whom I was dependent, and from whom I had received all that I possessed; for if I had existed alone, and independently of every other being, so as to have had from myself all the perfection, however little, which I actually possessed, I should have been able, for the same reason, to have had from myself the whole remainder of perfection, of the want of which I was conscious, and thus could of myself have become infinite, eternal, immutable, omniscient, all-powerful, and, in fine, have possessed all the perfections which I could recognize in God. For in order to know the nature of God (whose existence has been established by the preceding reasonings), as far as my own nature permitted, I had only to consider in reference to all the properties of which I found in my mind some idea, whether their possession was a mark of perfection; and I was assured that no one which indicated any imperfection was in him, and that none of the rest was awanting. Thus I perceived that doubt, inconstancy, sadness, and such like, could not be found in God, since I myself would have been happy to be free from them. Besides, I had ideas of many sensible and corporeal things; for although I might suppose that I was dreaming, and that all which I saw or imagined was false, I could not, nevertheless, deny that the ideas were in reality in my thoughts. But, because I had already very clearly recognized in myself that the intelligent nature is distinct from the corporeal, and as I observed that all composition is an evidence of dependency, and that a state of dependency is manifestly a state of imperfection, I therefore determined that it could not be a perfection in God to be compounded of these two natures and that consequently he was not so compounded; but that if there were any bodies in the world, or even any intelligences, or other natures that were not wholly perfect, their existence depended on his power in such a way that they could not subsist without him for a single moment.
Next, I reflected on the fact that I doubted and therefore was not wholly perfect. For I clearly saw that knowing was a greater perfection than doubting. This led me to ask where I had learned to think of something more perfect than myself. I clearly recognized that this idea must come from a being that really was more perfect. I had less difficulty explaining my thoughts about many other things outside me. These included the sky, the earth, light, heat, and a thousand other things. For I noticed nothing in these ideas that seemed to make them superior to me. So I could believe that, if these ideas were true, they arose from my own nature insofar as it possessed some perfection. If these ideas were false, I could believe they came from nothing. In other words, they existed in me because of some imperfection in my nature. But this explanation could not apply to the idea of a being more perfect than myself. For that idea to come from nothing was clearly impossible. Something more perfect cannot be an effect of, and depend on, something less perfect. That is no less contradictory than something coming from nothing. So it was equally impossible for this idea to have come from me. The only remaining possibility was that a being genuinely more perfect than myself had placed the idea in me. This being also possessed every perfection I could conceive of. In a word, this being was God. I added that, since I knew of some perfections I did not possess, I was not the only being in existence. With your permission, I will freely use the terms of scholastic philosophy here. On the contrary, there necessarily existed another, more perfect being on whom I depended. From this being I had received everything I possessed. For suppose I had existed alone, independently of every other being. Then whatever perfection I actually possessed, however little, would have come from myself. For the same reason, I could have given myself every remaining perfection I knew I lacked. Thus, by myself, I could have become infinite, eternal, unchanging, all-knowing, and all-powerful. In short, I could have possessed every perfection I could recognize in God. The preceding arguments had established God's existence. To understand his nature as far as my own nature allowed, I needed only to examine my ideas of properties. For each property, I had to consider whether possessing it was a mark of perfection. I was certain that God possessed no property indicating any imperfection, and that he lacked none of the others. Thus I saw that doubt, inconstancy, sadness, and similar things could not be found in God. For I myself would have been happy to be free of them. Besides, I had ideas of many things perceived through the senses and of many physical things. I might suppose I was dreaming and that everything I saw or imagined was false. Even so, I could not deny that these ideas really existed in my thoughts. But I had already recognized very clearly in myself that a thinking nature is distinct from a bodily nature. I also observed that anything made up of parts shows dependence, and that dependence is clearly a state of imperfection. So I concluded that being composed of these two natures could not be a perfection in God. Therefore, God was not composed of them. But if any bodies existed in the world, their existence depended on his power. The same applied to any minds or other beings that were not wholly perfect. They could not continue to exist without him for a single moment.
I was disposed straightway to search for other truths and when I had represented to myself the object of the geometers, which I conceived to be a continuous body or a space indefinitely extended in length, breadth, and height or depth, divisible into divers parts which admit of different figures and sizes, and of being moved or transposed in all manner of ways (for all this the geometers suppose to be in the object they contemplate), I went over some of their simplest demonstrations. And, in the first place, I observed, that the great certitude which by common consent is accorded to these demonstrations, is founded solely upon this, that they are clearly conceived in accordance with the rules I have already laid down In the next place, I perceived that there was nothing at all in these demonstrations which could assure me of the existence of their object: thus, for example, supposing a triangle to be given, I distinctly perceived that its three angles were necessarily equal to two right angles, but I did not on that account perceive anything which could assure me that any triangle existed: while, on the contrary, recurring to the examination of the idea of a Perfect Being, I found that the existence of the Being was comprised in the idea in the same way that the equality of its three angles to two right angles is comprised in the idea of a triangle, or as in the idea of a sphere, the equidistance of all points on its surface from the center, or even still more clearly; and that consequently it is at least as certain that God, who is this Perfect Being, is, or exists, as any demonstration of geometry can be.
I was ready to begin searching for other truths at once. I pictured the object studied by geometers as a continuous body or space extending indefinitely in length, width, and depth. This body or space could be divided into various parts with different shapes and sizes. These parts could be moved or rearranged in all kinds of ways. (Geometers assume all these properties in the object they study.) I then reviewed some of their simplest proofs. First, I noticed why everyone agrees that these proofs are so certain. Their certainty rests solely on our clearly understanding them according to the rules I have already laid down. Next, I realized that nothing in these proofs could assure me that the object they describe exists. For example, suppose a triangle is given. I clearly understood that its three angles must add up to two right angles. But this understanding gave me no assurance that any triangle existed. By contrast, I returned to examining the idea of a Perfect Being. I found that existence was included in this idea. In the same way, the idea of a triangle includes its three angles adding up to two right angles. Likewise, the idea of a sphere includes every point on its surface being equally distant from its center. Indeed, existence was included in the idea of a Perfect Being even more clearly than these properties in those shapes. Consequently, it is at least as certain that God, who is this Perfect Being, exists as any geometric proof.
But the reason which leads many to persuade them selves that there is a difficulty in knowing this truth, and even also in knowing what their mind really is, is that they never raise their thoughts above sensible objects, and are so accustomed to consider nothing except by way of imagination, which is a mode of thinking limited to material objects, that all that is not imaginable seems to them not intelligible. The truth of this is sufficiently manifest from the single circumstance, that the philosophers of the schools accept as a maxim that there is nothing in the understanding which was not previously in the senses, in which however it is certain that the ideas of God and of the soul have never been; and it appears to me that they who make use of their imagination to comprehend these ideas do exactly the some thing as if, in order to hear sounds or smell odors, they strove to avail themselves of their eyes; unless indeed that there is this difference, that the sense of sight does not afford us an inferior assurance to those of smell or hearing; in place of which, neither our imagination nor our senses can give us assurance of anything unless our understanding intervene.
But many convince themselves that knowing this truth is difficult, as is knowing what their mind really is. The reason is that they never think beyond objects perceived by the senses. They are so used to considering everything through imagination, a way of thinking limited to material objects, that they see anything they cannot imagine as impossible to understand. One fact alone makes this clear enough. The philosophers of the schools accept the principle that nothing enters the understanding without first passing through the senses. Yet the ideas of God and the soul have certainly never come through the senses. To me, people who use imagination to understand these ideas are doing exactly the same as someone trying to hear sounds or smell odors with their eyes. There is, however, one difference. Sight gives us no less certainty than smell or hearing. By contrast, neither imagination nor the senses can give us certainty about anything unless our understanding also plays a part.
Finally, if there be still persons who are not sufficiently persuaded of the existence of God and of the soul, by the reasons I have adduced, I am desirous that they should know that all the other propositions, of the truth of which they deem themselves perhaps more assured, as that we have a body, and that there exist stars and an earth, and such like, are less certain; for, although we have a moral assurance of these things, which is so strong that there is an appearance of extravagance in doubting of their existence, yet at the same time no one, unless his intellect is impaired, can deny, when the question relates to a metaphysical certitude, that there is sufficient reason to exclude entire assurance, in the observation that when asleep we can in the same way imagine ourselves possessed of another body and that we see other stars and another earth, when there is nothing of the kind. For how do we know that the thoughts which occur in dreaming are false rather than those other which we experience when awake, since the former are often not less vivid and distinct than the latter? And though men of the highest genius study this question as long as they please, I do not believe that they will be able to give any reason which can be sufficient to remove this doubt, unless they presuppose the existence of God. For, in the first place even the principle which I have already taken as a rule, viz., that all the things which we clearly and distinctly conceive are true, is certain only because God is or exists and because he is a Perfect Being, and because all that we possess is derived from him: whence it follows that our ideas or notions, which to the extent of their clearness and distinctness are real, and proceed from God, must to that extent be true. Accordingly, whereas we not infrequently have ideas or notions in which some falsity is contained, this can only be the case with such as are to some extent confused and obscure, and in this proceed from nothing (participate of negation), that is, exist in us thus confused because we are not wholly perfect. And it is evident that it is not less repugnant that falsity or imperfection, in so far as it is imperfection, should proceed from God, than that truth or perfection should proceed from nothing. But if we did not know that all which we possess of real and true proceeds from a Perfect and Infinite Being, however clear and distinct our ideas might be, we should have no ground on that account for the assurance that they possessed the perfection of being true.
Finally, some people may still doubt the existence of God and the soul, despite the reasons I have given. I want them to know that all the other claims they perhaps feel more certain about are less certain. These include the claims that we have a body, that stars and an earth exist, and similar claims. We do have a practical certainty about these things, so strong that doubting their existence seems absurd. But when it comes to metaphysical certainty, no one whose intellect is unimpaired can deny that grounds for doubt remain. While asleep, we can likewise imagine having another body and seeing other stars and another earth, although none exist. How do we know that our thoughts in dreams are false, rather than our thoughts while awake? After all, our thoughts in dreams are often just as vivid and distinct as our waking thoughts. Even if the most gifted minds study this question as long as they please, I do not believe they can resolve it. Unless they assume God's existence, they cannot give a reason sufficient to remove this doubt. First, consider the principle I have already adopted as a rule: everything we clearly and distinctly conceive is true. This principle is certain only because God exists, because he is a perfect being, and because everything we possess comes from him. Our ideas or notions are real to the extent that they are clear and distinct. And because they come from God, they must be true to that same extent. Yet we quite often have ideas or notions containing some falsehood. Such ideas can only contain falsehood insofar as they are confused and obscure. In that respect, they come from nothing (they involve a lack of being). In other words, these ideas are confused in us because we are not wholly perfect. Clearly, falsehood or imperfection, insofar as it is imperfection, cannot come from God, any more than truth or perfection can come from nothing. But suppose we did not know that everything real and true in us comes from a perfect and infinite being. Then, however clear and distinct our ideas might be, their clarity and distinctness would give us no grounds for certainty. We could not be sure that our ideas possessed the perfection of being true.
But after the knowledge of God and of the soul has rendered us certain of this rule, we can easily understand that the truth of the thoughts we experience when awake, ought not in the slightest degree to be called in question on account of the illusions of our dreams. For if it happened that an individual, even when asleep, had some very distinct idea, as, for example, if a geometer should discover some new demonstration, the circumstance of his being asleep would not militate against its truth; and as for the most ordinary error of our dreams, which consists in their representing to us various objects in the same way as our external senses, this is not prejudicial, since it leads us very properly to suspect the truth of the ideas of sense; for we are not infrequently deceived in the same manner when awake; as when persons in the jaundice see all objects yellow, or when the stars or bodies at a great distance appear to us much smaller than they are. For, in fine, whether awake or asleep, we ought never to allow ourselves to be persuaded of the truth of anything unless on the evidence of our reason. And it must be noted that I say of our reason, and not of our imagination or of our senses: thus, for example, although we very clearly see the sun, we ought not therefore to determine that it is only of the size which our sense of sight presents; and we may very distinctly imagine the head of a lion joined to the body of a goat, without being therefore shut up to the conclusion that a chimaera exists; for it is not a dictate of reason that what we thus see or imagine is in reality existent; but it plainly tells us that all our ideas or notions contain in them some truth; for otherwise it could not be that God, who is wholly perfect and veracious, should have placed them in us. And because our reasonings are never so clear or so complete during sleep as when we are awake, although sometimes the acts of our imagination are then as lively and distinct, if not more so than in our waking moments, reason further dictates that, since all our thoughts cannot be true because of our partial imperfection, those possessing truth must infallibly be found in the experience of our waking moments rather than in that of our dreams.
But once knowledge of God and the soul has made us certain of this rule, we can easily understand something further. The illusions of our dreams should not cast the slightest doubt on the truth of our waking thoughts. Suppose someone had a very clear idea while asleep. For example, a geometer might discover a new proof. Being asleep would not count against the truth of that proof. The most common error in dreams is that they present various objects just as our external senses do. But this error does no harm, because it rightly leads us to question the truth of our sensory ideas. For our senses often deceive us in the same way when we are awake. People with jaundice see everything as yellow. Stars and other distant bodies appear much smaller than they are. In short, whether awake or asleep, we should never accept anything as true except on the evidence of reason. Notice that I say reason, not imagination or the senses. For example, although we see the sun very clearly, we should not conclude that it is only as large as it looks. And we may imagine very clearly a lion’s head joined to a goat’s body. But imagining this does not force us to conclude that a chimaera exists. Reason does not tell us that what we see or imagine actually exists. But reason plainly tells us that all our ideas or notions contain some truth. Otherwise, God, who is wholly perfect and truthful, could not have placed those ideas in us. Our reasoning is never as clear or complete during sleep as when we are awake. Yet our imagination can sometimes be just as vivid and clear during sleep, if not more so. Because our reasoning is less clear during sleep, reason tells us something further. Since our thoughts cannot all be true because we are partly imperfect, we must look for truth in waking experience. Thoughts that contain truth must certainly be found there rather than in our dreams.