"Cogito ergo sum." (I think, therefore I am.)
Rene Descartes

"Everything is self-evident."
Rene Descartes

"Except our own thoughts, there is nothing absolutely in our power."
Rene Descartes

"I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake."
Rene Descartes

"When it is not in our power to follow what is true, we ought to follow what is most probable."
Rene Descartes

"If you want be a real seeker of truth, it is necessary that at least once in your life you doubt, as far as possible, all things."
Rene Descartes

"The first precept was never to accept a thing as true until I knew it as such without a single doubt."
Rene Descartes

"Divide each difficulty into as many parts as is feasible and necessary to resolve it.'
Rene Descartes

"Each problem that I solved became a rule which served afterwards to solve other problems."
Rene Descartes

"The reading of all good books is indeed like a conversation with the noblest men of past centuries who were the authors of them, no a carefully studied conversation, in which they reveal to us none but the best of their thoughts."
Rene Descartes

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

"It is not enough to have a good mind. The main thing is to use it well."
Rene Descartes

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

"It is only prudent never to place complete confidence in that by which we have even once been deceived.'
Rene Descartes

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

"Illusory joy is often worth more than genuine sorrow."
Rene Descartes

"Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it."
Rene Descartes