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

Feminine traits are called weaknesses. People joke about them; fools ridicule them; but reasonable persons see very well that those traits are just the tools for the management of men, and for the use of men for female designs.

Man's greatest concern is to know how he shall properly fill his place in the universe and correctly understand what he must be in order to be a man.

God, freedom, and immortality are untenable in the light of pure reason.

With men, the state of nature is not a state of peace, but war.

[R]eason is... given to us as a practical faculty, that is, as one that influences the will.

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