French Philosopher, Mathematician and Writer, called "Father of Modern Philosophy"
"What am I? A thing which thinks. What is a thing which thinks? It is a thing which doubts, understands, affirms, denies, wills, refuses, which also imagines and feels."
"When any one has offended me, I try to raise my soul so high that the offense cannot reach it."
"The passion of desire is an agitation of the soul caused by the spirits which dispose it to wish for the future the things which it represents to itself as agreeable. Thus we do not only desire the presence of the absent good, but also the conservation of the present, and further, the absence of evil, both of that which we already have, and of that which we believe we might experience in time to come."
"There is no better means of arriving at a knowledge of our passions than to examine the difference which exists between soul and body in order to know to which of the two we must attribute each one of the functions which are within us."
"The desire to repel harmful things and to revenge oneself, is the most persistent of all desires."
"The end of study should be to direct the mind towards the enunciation of sound and correct judgments on all matters that come before it."
"Pity is a species of sadness, mingled with love or good-will towards those whom we see suffering some evil of which we consider them undeserving."
"Reason already persuades me that I ought no less carefully to withhold my assent from matters which are not entirely certain and indubitable than from those which appear to me manifestly to be false, if I am able to find in each one some reason to doubt."
"It is now some years since I detected how many were the false beliefs that I had believed to be true since my earliest youth. And since that time, I have been convinced that I must once and for all seriously try to rid myself of all the opinions which I had formerly accepted and begin to build anew, if I wanted to establish any firm and permanent structure for my beliefs."
"Jealousy is a species of fear which is related to the desire we have to preserve to ourselves the possession of some thing."
"In the subjects we propose to investigate, our inquiries should be directed, not to what others have thought, nor to what we ourselves conjecture, but to what we can clearly and perspicuously behold and with certainty deduce; for knowledge is not won in any other way."
"If you would be a real seeker after truth, you must at least once in your life doubt, as far as possible, all things."
"Hope is a disposition of the soul to persuade itself that what it desires will come to pass."
"As to the freedom of the will, a very different account must be given of it as it exists in God and as its exists for us... That idea of good impelled God to choose one thing rather than another... Thus that supreme indifference in God is the supreme proof of his omnipotence. But as to man, since he finds the nature of all goodness and truth already determined by God, and his will cannot bear upon anything else, it is evident that he embraces the true and the good the more willingly and hence the more freely in proportion as he sees the true and the good more clearly, and that he is never indifferent save when he does not know what is the more true or the better, or at least when he does not see clearly enough to prevent him from doubting about it. Thus the indifference which attaches to human liberty is very different from that which belongs to the divine."
"For just as faith teaches us that the supreme felicity of the other life consists only in this contemplation of the Divine Majesty, so we continue to learn by experience that a similar meditation, though incomparably less perfect, causes us to enjoy the greatest satisfaction of which we are capable of in this life."
"Examining attentively that which I was, I saw that I could conceive that I had no body, and that there was no world nor place where I might be; but yet that I could not for all that conceive that I was not. On the contrary, I saw from the very fact that I thought of doubting the truth of other things, it very evidently and certainly followed that I was; on the other hand if I had only ceased from thinking, even if all the rest of what I had ever imagined had really existed, I should have no reason for thinking that I had existed. From that I knew that I was a substance the whole essence or nature of which is to think, and that for its existence there is no need of any place, nor does it depend on any material thing; so that this ‘me,’ that is to say, the soul by which I am what I am, is entirely distinct from body, and is even more easy to know than is the latter; and even if body were not, the soul would not cease to be what it is."
"Except our own thoughts, there is nothing absolutely in our power... The principal effect of the passions is that they incite and persuade the mind to will the events for which they prepared the body... If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."
"After having reflected well and carefully examined all things, we must come to the definite conclusion that this proposition: I am, I exist, is necessarily true each time that I pronounce it, or that I mentally conceive it."
"Good sense is the best distributed thing in the world: for everyone thinks himself so well endowed with it that even those who are the hardest to please in everything else do not usually desire more of it than they possess. In this it is unlikely that everyone is mistaken. It indicates rather that the power of judging well and of distinguishing the true from the false - which is what we properly call ‘good sense’ - is naturally equal in all men."
"Reading good books is like having a conversation with the highly worthy persons of the past who wrote them; indeed, it is like having a prepared conversation in which those persons disclose to us only their best thinking."
"The reading of all good books is indeed like a conversation with the noblest men of past centuries who were the authors of them, nay a carefully studied conversation, in why they revel to us none but the best of their thoughts."
"This ‘I’ - that is, the soul by which I am what I am - is entirely distinct from the body, and indeed is easier to know than the body, and would not fail to be whatever it is, even if the body did not exist."
"To one who pays attention to God’s immensity, it is clear that nothing at all can exist which does not depend on Him. This is true not only of everything that subsists, but of all order, of every law, and of every reason of truth and goodness... Hence, neither should we think that eternal truths depend upon the human understanding or on other existing things; they must depend on God alone, who as the supreme legislator, ordained them from all eternity."
"There is a great difference between the mind and the body, inasmuch as the body is by its very nature always divisible, while the mind is utterly indivisible."
"I conceive God as actually infinite, so that nothing can be added to her perfection. And, in fine, I readily perceive that the objective being of an idea cannot be produced by a being that is merely potentially existent, which, properly speaking, is nothing, but only by a being existing formally and actually."
"I discover what properly belongs to myself. This alone is inseparable from me. I am, I exist; this is certain."
"We have in the notion of God absolute immensity, simplicity, and a unity that embraces all other attributes; and of this idea we find no example in us."
"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."
"I will now close my eyes, I will stop my ears, I will turn away my senses from their objects, I will even efface from my consciousness all the images of corporeal things; or at least, because this can hardly be accomplished, I will consider them as empty and false; and thus, holding converse only with myself, and closely examining my nature, I will endeavour to obtain by degrees a more intimate and familiar knowledge of myself."
"Revealed truths are above our intelligence, and I would not dare submit them to the feebleness of my reason."
"What is man? Shall I say a rational animal?… a thinking being, that is to say, a mind, an understanding, or a reasonable being… A thing which thinks."
"The multitude of laws frequently furnishes an excuse for vice, and a state is better governed with a few laws which are strictly adhered to."
"We should never allow ourselves to be persuaded excepting by the evidence of our Reason, of our Reason and not our imagination nor of our senses."
"A way to make people generally more wise and more skillful than they have been in the past, I believe that we should look for it in medicine. It is true that medicine as it is currently practiced contains little of much use."
"And the final rule was: in all cases, to make such comprehensive enumerations and such general review that I was certain not to omit anything."
"As I considered the matter carefully it gradually came to light that all those matters only were referred to mathematics in which order and measurements are investigated, and that it makes no difference whether it be in numbers, figures, stars, sounds or any other object that the question of measurement arises. I saw consequently that there must be some general science to explain that element as a whole which gives rise to problems about order and measurement, restricted as these are to no special subject matter. This, I perceived was called 'universal mathematics'."
"After that, I thought about what a proposition generally needs in order to be true and certain because, since I had just found one that I knew was such, I thought I should also know what this certainty consists in. Having noticed that there is nothing at all in the proposition 'I think, therefore I am' [cogito ergo sum] which convinces me that I speak the truth, apart from the fact that I see very clearly that one has to exist in order to think, I judged that I could adopt as a general rule that those things we conceive very clearly and distinctly are all true. The only outstanding difficulty is in recognizing which ones we conceive distinctly."
"An optimist may see a light where there is none, but why must the pessimist always run to blow it out?"
"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."
"And there are absolutely no judgments (or rules) in Mechanics which do not also pertain to Physics, of which Mechanics is a part or type: and it is as natural for a clock, composed of wheels of a certain kind, to indicate the hours, as for a tree, grown from a certain kind of seed, to produce the corresponding fruit. Accordingly, just as when those who are accustomed to considering automata know the use of some machine and see some of its parts, they easily conjecture from this how the other parts which they do not see are made: so, from the perceptible effects and parts of natural bodies, I have attempted to investigate the nature of their causes and of their imperceptible parts."
"At last I will devote myself sincerely and without reservation to the general demolition of my opinions."