History is nothing but a problem of mechanics applied to psychology.

To have a true idea of man or of life, one must have stood himself on the brink of suicide, or on the door-sill of insanity, at least once.

The more I study the things of the mind the more mathematical I find them. In them as in mathematics it is a question of quantities; they must be treated with precision. I have never had more satisfaction than in proving this in the realms of art, politics and history.

The search for causes must come after the collection of facts.

I've met many thinkers and many cats, but the wisdom of cats is infinitely superior.

For thirty centuries, from her sacred seat the cat looked down, and crouching at her feet, beheld the race of conquering Pharaohs kneel.

I wish to reproduce things as they are or as they would be even if I myself did not exist.