René Descartes

The power of judging well and of distinguishing the true from the false, which is properly what is called good sense or reason, is by nature equal in all men.

I concluded that I was a substance whose whole essence or nature resides only in thinking, and which, in order to exist, has no need of place and depends on no material thing.

The greatest good is to live without fear.

Perfect numbers, like perfect men, are very rare.

Mathematics is the language in which God has written the universe.

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

I hope that posterity will judge me kindly, not only as to the things which I have explained, but also as to those which I have intentionally omitted so as to leave to others the pleasure of discovery.

The mind, when it is well directed, is capable of discovering the truth.

All that is clearly and distinctly perceived is true.

The very fact that I can conceive of a perfect being implies that such a being must exist.

I am not a body, but a thinking substance.

I desire to live in peace and to continue the war against the passions.

I have never found that my mind was more free or that I was more master of myself than when I was in the country.

I believe that all things that can be known, can be known by mathematics.

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

It is true that I have never been able to find any reason for believing that the soul perishes with the body.

Give me extension and motion, and I will construct the universe.

I have always been of the opinion that the two questions respecting God and the Soul were the chief of those that ought to be demonstrated by the help of philosophy rather than of theology.

I confess that I have never been able to find any reason for believing that the soul perishes with the body.

I have learned to distrust my senses, for they have often deceived me.