A thing is not proved because no one has ever questioned it... Skepticism is the first step toward truth.

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.

Fanaticism is just one step away from barbarism.

There is less harm to be suffered in being mad among madmen than in being sane all by oneself.

There is not a Musselman alive who would not imagine that he was performing an action pleasing to God and his Holy Prophet by exterminating every Christian on earth, while the Christians are scarcely more tolerant on their side.

The philosopher forms his principles on an infinity of particular observations. He does not confuse truth with plausibility, he takes for truth what is true, for false what is false, for doubtful what is doubtful, and probable what is probable. The philosophical spirit is thus a spirit of observation and accuracy.

Happiest are the people who give most happiness to others.