Oh! how near are genius and madness! Men imprison them and chain them, or raise statues to them.

A thing is not proved just because no one has ever questioned it. What has never been gone into impartially has never been properly gone into. Hence scepticism is the first step toward truth. It must be applied generally, because it is the touchstone.

I have not the hope of being immortal, because the desire of it has not given me that vanity.

There is only one virtue, justice; only one duty, to be happy; only one corollary, not to overvalue life and not to fear death.

Fanaticism is just one step away from barbarism.

I like better for one to say some foolish thing upon important matters than to be silent. That becomes the subject of discussion and dispute, and the truth is discovered.

My friend, you should blow out your candle in order to find your way more clearly.