Our passions are ourselves.

It is almost impossible systematically to constitute a natural moral law. Nature has no principles. She furnishes us with no reason to believe that human life is to be respected. Nature, in her indifference, makes no distinction between good and evil.

Do not try to satisfy your vanity by teaching a great many things. Awaken people's curiosity. It is enough to open minds; do not overload them. Put there just a spark. If there is some good inflammable stuff, it will catch fire.

Change is the essence of life.

Never lend books, for no one ever returns them; the only books I have in my library are books that other folks have left me.

That man is prudent who neither hopes nor fears anything from the uncertain events of the future.

Religion has done love a great service by making it a sin.