A man must know how to fly in the face of opinion; a woman to submit to it.

Love is the whole history of a woman's life, it is but an episode in a man's.

Scientific progress makes moral progress a necessity; for if man's power is increased, the checks that restrain him from abusing it must be strengthened.

One must choose in life between boredom and suffering.

Search for the truth is the noblest occupation of man; its publication is a duty.

Love is a symbol of eternity. It wipes out all sense of time, destroying all memory of a beginning and all fear of an end.