Quotes from Rene Descartes

For 'tis not enough to have good faculties, but the principal is, to apply them well.

If I find some reason for doubt in each of my beliefs, that will be enough to reject all of them.

Je puis me persuader d'avoir été fait tel par la nature que je puisse aisément me tromper même dans les choses que je crois comprendre avec le plus d'évidence et de certitude.

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 am thinking, therefore I exist.

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

For indeed when painters themselves wish to represent sirens and satyrs [20] by means of especially bizarre forms, they surely cannot assign to them utterly new natures. Rather, they simply fuse together the members of various animals. Or if perhaps they concoct something so utterly novel that nothing like it has ever been seen before (and thus is something utterly fictitious and false), yet certainly at the very least the colors from which they fashion it ought to be true. And

was most keen on mathematics, because of its certainty and the incontrovertibility* of its proofs; but I did not yet see its true use. Believing as I did that its only application was to the mechanical arts,* I was astonished that nothing more exalted had been built on such sure and solid foundations; whereas, on the other hand, I compared the moral works of ancient pagan writers to splendid and magnificent palaces built on nothing more than sand and mud.

we ought also to consider as false all that is doubtful.

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.

One cannot conceive anything so strange and so implausible that it has not already been said by one philosopher or another.

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

they who make pretensions to philosophy are often less wise and reasonable than others who never applied themselves to the study

while I wanted thus to think that everything was false, it necessarily had to be the case that I, who was thinking this, was something. And noticing that this truth—I think, therefore I am—was so firm and so assured that all the most extravagant suppositions of the skeptics were incapable of shaking it, I judged that I could accept it without scruple as the first principle of the philosophy I was seeking.

But, because I had already very clearly recognized in myself that the intelligent nature is distinct from the corporeal

For I found myself involved in so many doubts and errors, that I was convinced I had advanced no farther in all my attempts at learning, than the discovery at every turn of my own ignorance. And

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.

I was thus led to infer that the ground of our opinions is far more custom and example than any certain knowledge.

I entirely abandoned the study of letters. Resolving to seek no knowledge other than that of which could be found in myself or else in the great book of the world, I spent the rest of my youth traveling, visiting courts and armies, mixing with people of diverse temperaments and ranks, gathering various experiences, testing myself in the situations which fortune offered me, and at all times reflecting upon whatever came my way so as to derive some profit from it.

Con frecuencia una falsa alegría vale más que una tristeza cuya causa es verdadera.

About Pierre de Fermat] It cannot be denied that he has had many exceptional ideas, and that he is a highly intelligent man. For my part, however, I have always been taught to take a broad overview of things, in order to be able to deduce from them general rules, which might be applicable elsewhere.

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.

Gratitude is a species of love, excited in us by some action of the person for whom we have it, and by which we believe that he has done some good to us, or at least that he has had the intention of doing so. Passions, III, 193. XI, 473-474. Trans. John Morris

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.