People live for the morrow, because the day-after-to-morrow is doubtful.

The destiny of the human race is to widen the gap separating it from the lower races of animals. Any code of morality which retains its permanence and authority after the conditions of existence which gave rise to it have changed, works against this upward progress of man.

Truth will have no gods before it.- The belief in truth begins with the doubt of all truths in which one has previously believed.

Art is the great stimulus to life.

The world was conquered through the understanding of dogs; the world exists through the understanding of dogs.

Stupid as a man, say the women: cowardly as a woman, say the men. Stupidity in a woman is unwomanly.

The believer in magic and miracles reflects on how to impose a law on nature--: and, in brief, the religious cult is the outcome of this reflection.