French "philosopher, mathematician, scientist".
He was called the father of modern philosophy; inventor of analytic geometry and several advances in optics.
Traveling is almost like talking with men of other centuries.
"Except our own thoughts, there is nothing absolutely in our power."
The first precept was never to accept a thing as true until I knew it as such without a single doubt.
It is not enough to have a good mind. The main thing is to use it well.
Everybody thinks himself so well supplied with common sense that even those most difficult to please. . . never desire more of it than they already have.
