There is no supernatural, there is only nature. Nature alone exists and contains all. All is. There is the part of nature that we perceive, and the part of nature that we do not perceive. ... If you abandon these facts, beware; charlatans will light upon them, also the imbecile. There is no mean: science, or ignorance. If science does not want these facts, ignorance will take them up. You have refused to enlarge human intelligence, you augment human stupidity. When Laplace withdraws Cagliostro appears.

A man is not idle because he is absorbed in thought. There is a visible labor and there is an invisible labor.

True or false, that which is said of men often occupies as important a place in their lives, and above all in their destinies, as that which they do.

Morality is truth in full bloom.

He never went out without a book under his arm, and he often came back with two.

It is not enough to be happy, one must be content.

God was bored by him.