Humor is not a mood but a way of looking at the world. So if it is correct to say that humor was stamped out in Nazi Germany, that does not mean that people were not in good spirits, or anything of that sort, but something much deeper and more important.

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.

The popular scientific books by our scientists aren't the outcome of hard work, but are written when they are resting on their laurels.

The world is the totality of facts, not of things

The common behavior of mankind is the system of reference by means of which we interpret an unknown language.

In order to be able to set a limit to thought, we should have to find both sides of the limit thinkable (i.e. we should have to be able to think what cannot be thought).

Philosophy aims at the logical clarification of thoughts. Philosophy is not a body of doctrine but an activity. A philosophical work consists essentially of elucidations.