Rene Descartes Quotes

...we ought not meanwhile to make use of doubt in the conduct of life.

Every man is indeed bound to do what he can to promote the good of others, and a man who is of no use to anyone is strictly worthless.

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.

Nature teaches me that so many other bodies exist around mine of which some are to be avoided, some sought after.

Bad books engender bad habits, but bad habits engender good books.

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.

Nothing comes out of nothing.

We never understand a thing so well,and make it our own, as when we have discovered it for ourselves.

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;

To think? That's it. It is thought. This alone cannot be detached from me. I am, I exist; that is certain.

Moral certainty is certainty which is sufficient to regulate our behaviour, or which measures up to the certainty we have on matters relating to the conduct of life which we never normally doubt, though we know that it is possible, absolutely speaking, that they may be false.

I knew that the languages which one learns there are necessary to understand the works of the ancients; and that the delicacy of fiction enlivens the mind; that famous deeds of history ennoble it and, if read with understanding, aid in maturing one's judgment; that the reading of all the great books is like conversing with the best people of earlier times; it is even studied conversation in which the authors show us only the best of their thoughts; that eloquence has incomparable powers and beauties; that poetry has enchanting delicacy and sweetness; that mathematics has very subtle processes which can serve as much to satisfy the inquiring mind as to aid all the arts and diminish man's labor; that treatises on morals contain very useful teachings and exhortations to virtue; that theology teaches us how to go to heaven; that philosophy teaches us to talk with appearance of truth about things, and to make ourselves admired by the less learned; that law, medicine, and the other sciences bring honors and wealth to those who pursue them; and finally, that it is desirable to have examined all of them, even to the most superstitious and false in order to recognize their real worth and avoid being deceived thereby

So that even although he had from the beginning given it no other form than that of chaos, provided only he had established certain laws of nature, and had lent it his concurrence to enable it to act as it is wont to do, it may be believed, without discredit to the miracle of creation, that, in this way alone, things purely material might, in course of time, have become such as we observe them at present; and their nature is much more easily conceived when they are beheld coming in this manner gradually into existence, than when they are only considered as produced at once in a finished and perfect state.

On the other hand, I compared the disquisitions of the ancient moralists to very towering and magnificent palaces with no better foundation than sand and mud:

Science is practical philosophy.

My third maxim was to try always to master myself rather than fortune and change my desires rather than changing how things stand in the world.

We do not describe the world we see, we see the world we can describe.

Thus each truth discovered was a rule available in the discovery of subsequent ones.

Truths are more likely to have been discovered by one man than by nation

...the greater objective (representative) perfection there is in our idea of a thing, the greater also must be the perfection of its cause.

A person has two passions for love and abhorrence. A big disposition to excessiveness has just a love, because it is more ardent and stronger.

Good sense is the most evenly distributed thing in the world; for everyone believes himself to be so well provided with it that even those who are the hardest to please in every other way do not usually want more of it than they already have.

To attain the truth in life, we must discard all the ideas we were taught.

The mind effortlessly and automatically takes in new ideas, which remain in limbo until verified or rejected by conscious, rational analysis.

Booty Butt, Booty Butt, Booty Butt Cheeks

I am thing that thinks: that is, a things that doubts,affirms, denies, understands a few things, is ignorant of many things, is willing, is unwilling, and also which imagines and has sensory perceptions.

And what more am I? I look for aid to the imagination. [But how mistakenly!] I am not that assemblage of limbs we call the human body; I am not a subtle penetrating air distributed throughout all these members; I am not a wind, a fire, a vapor, a breath or anything at all that I can image. I am supposing all these things to be nothing. Yet I find, while so doing, that I am still assured that I am a something.

Even those who have the weakest souls could acquire absolute mastery over all their passions if we employed sufficient ingenuity in training and guiding them.

Certainly no one can deny that we have such an idea of God in ourselves unless they think that there is no knowledge at all of God in human minds.

The principal use of prudence, of self-control, is that it teaches us to be masters of our passions, and to so control and guide them that the evils which they cause are quite bearable, and that we even derive joy from them all.

But possibly I am something more than I suppose myself to be.

Nothing can be imagined which is too strange or incredible to have been said by some philosopher.

The chief cause of human errors is to be found in the prejudices picked up in childhood.

As regards the soul, many people thought that its nature cannot easily be investigated, and some have even dared say that human reason shows us that the soul dies with the body and that the contrary view is held by faith alone; however, the Lateran Council, held under Leo X (Session 8), condemns them and explicitly commands Christian philosophers to defeat their arguments and prove the truth to the best of their abilities, and therefore I too have not hesitated to take on this challenge.

I should consider that I know nothing about physics if I were able to explain only how things might be, and were unable to demonstrate that they could not be otherwise.

In order to improve the mind, we ought less to learn than to contemplate.

Few look for truth; many prowl about for a reputation of profundity by arrogantly challenging whichever arguments are the best.

And, in fine, of false sciences I thought I knew the worth sufficiently to escape being deceived by the professions of an alchemist, the predictions of an astrologer, the impostures of a magician, or by the artifices and boasting of any of those who profess to know things of which they are ignorant.

Good sense is, of all things among men, the most equally distributed; for every one thinks himself so abundantly provided with it, that those even who are the most difficult to satisfy in everything else, do not usually desire a larger measure of this quality than they already possess.

Moreover, I am aware that most of the irreligious deny the existence of God, and the distinctness of the human soul from the body, for no other reason than because these points, as they allege, have never as yet been demonstrated.

I revered our theology, and aspired as much as any one to reach heaven: but being given assuredly to understand that the way is not less open to the most ignorant than to the most learned, and that the revealed truths which lead to heaven are above our comprehension, I did not presume to subject them to the impotency of my reason; and I thought that in order competently to undertake their examination, there was need of some special help from heaven, and of being more than man.

And thus, the actions of life often not allowing any delay, it is a truth very certain that, when it is not in our power to determine the most true opinions we ought to follow the most probable.

Regarding speculative matters that are of no practical moment, and followed by no consequences to himself, farther, perhaps, than that they foster his vanity the better the more remote they are from common sense; requiring, as they must in this case, the exercise of greater ingenuity and art to render them probable.

It is a mark of prudence never to place our complete trust in those who have deceived us even once.

To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them.

The first was never to accept anything for true which I did not clearly know to be such; that is to say, carefully to avoid precipitancy and prejudice, and to comprise nothing more in my judgment than what was presented to my mind so clearly and distinctly as to exclude all ground of doubt.

I was especially delighted with the mathematics, on account of the certitude and evidence of their reasonings; but I had not as yet a precise knowledge of their true use; and thinking that they but contributed to the advancement of the mechanical arts, I was astonished that foundations, so strong and solid, should have had no loftier superstructure reared on them.

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'.

But what then am I? A thing that thinks. What is that? A thing that doubts, understand, affirms, denies, wills, refuses, and that also imagines and senses.

For, occupied incessantly with the consideration of the limits prescribed to their power by nature, they [philosophers of former times] became so entirely convinced that nothing was at their disposal except their own thoughts, that this conviction was of itself sufficient to prevent their entertaining any desire of other objects; and over their thoughts they acquired a sway so absolute, that they had some ground on this account for esteeming themselves more rich and more powerful, more free and more happy, than other men who, whatever be the favors heaped on them by nature and fortune, if destitute of this philosophy, can never command the realization of all their desires.

Any community that gets its laughs by pretending to be idiots will eventually be flooded by actual idiots who mistakenly believe that they're in good company.

Even the mind depends so much on temperament and the disposition of one's bodily organs that, if it is possible to find a way to make people generally more wise and more skilful 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.

It is contrary to reasoning to say that there is a vacuum or space in which there is absolutely nothing.

The destruction of the foundations necessarily brings down the whole edifice.

The perusal of all excellent books is, as it were, to interview with the noblest men of past ages, who have written them.

Good sense is of all things in the world the most equally distributed, for everybody thinks he is so well supplied with it that even those most difficult to please in all other matters never desire more of it than they already possess.

Perfect numbers like perfect men are very rare.

Bene vixit, bene qui latuit.
(to live well is to live concealed)

Mathematics is a more powerful instrument of knowledge than any other that has been bequeathed to us by human agency.

It must not be thought that it is ever possible to reach the interior earth by any perseverance in mining: both because the exterior earth is too thick, in comparison with human strength; and especially because of the intermediate waters, which would gush forth with greater impetus, the deeper the place in which their veins were first opened; and which would drown all miners.

How do we know that anything really exists, that anything is really the way it seems ot us through our senses?

One of the first of the considerations that occurred to me was that there is very often less perfection in works composed of several portions, and carried out by the hands of various masters, than in those on which one individual alone has worked. Thus we see that buildings planned and carried out by one architect alone are usually more beautiful and better proportioned than those which many have tried to put in order and improve, making use of old walls which were built with other ends in view.

Instead of René Descartes' famous "Cogito ergo sum" (I think, therefore I am), I propose "Communico ergo sum," (I communicate, therefore I exist") as the philosophical proof of man's existence.

Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.

I undertook to conquer myself rather than fortune , and to alter my desires rather than change the order of the world , and to accustom myself to believe that nothing is entirely in our power except our own thoughts .

Thought I had said enough respecting them to show that there is nothing observable in the heavens or stars of our system that must not, or at least may not appear precisely alike in those of the system which I described.

I had become aware, as early as my college days, that no opinion, however absurd and incredible can be imagined, that has not been held by one of the philosophers.

I was convinced that our beliefs are based much more on custom and example than on any certain knowledge.

One needs to know what thought is, what existence is and what certainty is.

Man, being finite in nature can only have knowledge perfectness of which is limited.

Mind and soul of the man is entirely different from the body.

I think, therefore I am" vs. "As a man thinks in his heart, so is he.

But I cannot forget that, at other times I have been deceived in sleep by similar illusions; and, attentively considering those cases, I perceive so clearly that there exist no certain marks by which the state of waking can ever be distinguished from sleep, that I feel greatly astonished; and in amazement I almost persuade myself that I am now dreaming.

Just as faith teaches us that the sovereign felicity of the other life consists in the contemplation of the divine majesty alone, so even now we can learn from experience that a similar meditation, although incomparably less perfect, allows us to enjoy the greatest happiness we are capable of feeling in this life.

And as it is the most generous souls who have most gratitude, it is those who have most pride, and who are most base and infirm, who most allow themselves to be carried away by anger and hatred.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

I accept no principles of physics which are not also accepted in mathematics.

What then is the source of my errors? They are owing simply to the fact that, since the will extends further than the intellect, I do not contain the will within the same boundaries; rather, I also extend it to things I do not understand. Because the will is indifferent in regard to such matters, it easily turns away from the true and the good; and in this way I am deceived and I sin.

Those who reason most powerfully and are the most successful at ordering their thoughts so as to make them clear and intelligible will always be best able to persuade others of what they say, even if they speak in the thickest of dialects

All that is necessary to right action is right judgment, and to the best action the most correct judgment

In order to seek truth, it is necessary once in the course of our life to doubt, as far as possible, of all things.

Suppose [a person] had a basket full of apples and, being worried that some of the apples were rotten, wanted to take out the rotten ones to prevent the rot spreading. How would he proceed? Would he not begin by tipping the whole lot out of the basket? And would not the next step be to cast his eye over each apple in turn, and pick up and put back in the basket only those he saw to be sound, leaving the others? In just the same way, those who have never philosophized correctly have various opinions in their minds which they have begun to store up since childhood, and which they therefore have reason to believe may in many cases be false. They then attempt to separate the false beliefs from the others, so as to prevent their contaminating the rest and making the whole lot uncertain. Now the best way they can accomplish this is to reject all their beliefs together in one go, as if they were all uncertain and false. They can then go over each belief in turn and re-adopt only those which they recognize to be true and indubitable.

We must in the end acknowledge the infirmity of our nature

I think; therefore I am.

Neither the true nor the false roots are always real; sometimes they are imaginary; that is, while we can always imagine as many roots for each equation as I have assigned, yet there is not always a definite quantity corresponding to each root we have imagined.

It is useful to know something of the manners of different nations, that we may be enabled to form a more correct judgment regarding our own, and be prevented from thinking that everything contrary to our customs is ridiculous and irrational, a conclusion usually come to by those whose experience has been limited to their own country.

I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me. I think I have no senses. I believe that body, shape, extension, motion, location are functions. What is there then that can be taken as true? Perhaps only this one thing, that nothing at all is certain.

Be that as it may, there is fixed in my mind a certain opinion of long [21] standing, namely that there exists a God who is able to do anything and by whom I, such as I am, have been created. How do I know that he did not bring it about that there is no earth at all, no heavens, no extended thing, no shape, no size, no place, and yet bringing it about that all these things appear to me to exist precisely as they do now?

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

I fear being shaken out of them because I am afraid that my peaceful sleep may be followed by hard labour when I wake, and that I shall have to struggle not in the light but in the imprisoning darkness of the problems I have raised.

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.

Truths are more likely to be discovered by one man than by a nation

It is just as valuable to be censured by friends as it is splendid to be praised by enemies. We desire praise from those who do not know us, but from friends we want the truth.

The only secure knowledge is that I exist.

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

It is not enough to have a good mind; the main thing is to use it well.

These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered.

Therefore from the fact alone that I know that I exist and that, at the same time, I notice absolutely nothing else that belongs to my nature apart from the single fact that I am a thinking thing, I correctly conclude that my essence consists in this alone, that I am a thinking thing.

I took especially great pleasure in mathematics because of the certainty and the evidence of its arguments.

Nothing is made from nothing.