Faith which does not doubt is dead faith.

Man dies of cold, not of darkness.

The skeptic does not mean him who doubts, but him who investigates or researches, as opposed to him who asserts and thinks that he has found.

Knowledge for the sake of knowledge! Truth for truth's sake! This is inhuman.

Cure yourself of the inclination to bother about how you look to other people. Be concerned only . . . with the idea God has of you.

These terrible sociologists, who are the astrologers and alchemists of our twentieth century.

If a philosopher is not a man, he is anything but a philosopher; he is above all a pedant, and a pedant is a caricature of a man.