Even a man's exact imitation of the song of the nightingale displeases us when we discover that it is a mimicry, and not the nightingale.

The death of dogma is the birth of morality.

The only thing that is good without qualification is a good will.

Enlightenment is man's emergence from his self-incurred immaturity.

Experience without theory is blind, but theory without experience is mere intellectual play.

Reason can never prove the existence of God.

Dare to know! Have the courage to use your own intelligence!