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.

We study ourselves three weeks, we love each other three months, we squabble three years, we tolerate each other thirty years, and then the children start all over again.

There are four types of men in the world: lovers, opportunists, lookers-on, and imbeciles. The happiest are the imbeciles.

Kindly politeness is the slow fruit of advanced reflection; it is a sort of humanity and kindliness applied to small acts and every day discourse: it bids man soften towards others, and forget himself for the sake of others: it constrains genuine nature, which is selfish and gross.

Amid this vast and overwhelming space and in these boundless solar archipelagoes, how small is our own sphere, and the earth, what a grain of sand!

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.