One must need to be strong, otherwise one will never become strong.

Out of damp and gloomy days, out of solitude, out of loveless words directed at us, conclusions grow up in us like fungus: one morning they are there, we know not how, and they gaze upon us, morose and gray. Woe to the thinker who is not the gardener but only the soil of the plants that grow in him.

In a friend one should have ones best enemy. You should be closest to him with your heart when you resist him.

Our knowledge will take its revenge on us, just as ignorance exacted its revenge during the Middle Ages.

Whoever has provoked men to rage against him has always gained a party in his favor, too.

But thought is one thing, the deed is another, and the image of the deed still another: the wheel of causality does not roll between them.

What makes us heroic?--Confronting simultaneously our supreme suffering and our supreme hope.