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

Rene Descartes

I think; therefore I am.

Rene Descartes

. . .to be useful to no one is, strictly speaking, to be worthless.

Rene Descartes

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

Rene Descartes

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

Rene Descartes

I know not if I was then a man dreaming I was a butterfly, or if I am now a butterfly dreaming I am a man.

Rene Descartes

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

Rene Descartes

The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.

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, nay a carefully studied conversation, in which they reveal to us none but the best of their thoughts.

Rene Descartes

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

Rene Descartes

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

Rene Descartes

Cogito ergo sum. (I think; therefore I am.)

Rene Descartes

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.

Rene Descartes

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

Rene Descartes