The dog is very smart. He feels sorry for me because I receive so much mail; that's why he tries to bite the mailman.

You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.

It would seem that men always need some idiotic fiction in the name of which they can hate one another. Once it was religion. Now it is the State.

I am not a positivist. Positivism states that what cannot be observed does not exist. This conception is scientifically indefensible, for it is impossible to make valid affirmations of what people 'can' or 'cannot' observe. One would have to say 'only what we observe exists,' which is obviously false.

One does not make wars less likely by formulationg rules of warfare... war cannot be humanized. It can only be eliminated.

The pursuit of truth and beauty is a sphere of activity in which we are permitted to remain children all our lives.

Insofar as mathematics is true, it does not describe the real world. Insofar as it describes the real world, it is not true.