If you tried to doubt everything you would not get as far as doubting anything. The game of doubting itself presupposes certainty.

Courage, not cleverness; not even inspiration, is the grain of mustard that grows up to be a great tree.

Nowadays it is the fashion to emphasize the horrors of the last war. I didn't find it so horrible. There are just as horrible things happening all round us today, if only we had eyes to see them.

Mathematics is a logical method. . . . Mathematical propositions express no thoughts. In life it is never a mathematical proposition which we need, but we use mathematical propositions only in order to infer from propositions which do not belong to mathematics to others which equally do not belong to mathematics.

We are asleep. Our Life is a dream. But we wake up sometimes, just enough to know that we are dreaming.

Genius is talent exercised with courage.

Not how the world is, but that it is, is the mystery.