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

Prudence reproaches; conscience accuses.

Riches ennoble a man's circumstances, but not himself.

We can never, even by the strictest examination, get completely behind the secret springs of action.

Metaphysics is a dark ocean without shores or lighthouse, strewn with many a philosophic wreck.

Through laziness and cowardice a large part of mankind, even after nature has freed them from alien guidance, gladly remain immature. It is because of laziness and cowardice that it is so easy for others to usurp the role of guardians. It is so comfortable to be a minor!

Have the courage to use your own reason- That is the motto of enlightenment. "Foundations of the Metaphysics of Morals" (1785)