"To be a good philosopher, one must be a good mathematician."

"I concluded that I was a substance whose whole essence or nature consists only in thinking, and that, in order to exist, it needs no place and depends on no material thing."

"I know that I exist, but I do not know what I am."

"I think, therefore I am."

"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…"