The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.

Your theory is crazy, but it's not crazy enough to be true.

We depend on our words... Our task is to communicate experience and ideas to others. We must strive continually to extend the scope of our description, but in such a way that our messages do not thereby lose their objective or unambiguous character... We are suspended in language in such a way that we cannot say what is up and what is down. The word "reality" is also a word, a word which we must learn to use correctly.

There is no hope for any speculation that does not look absurd at first glance.

There are some things so serious you have to laugh at them.

Sometimes the child in one behaves a certain way and the rest of oneself follows behind, slowly shaking its head.

A physicist visits a colleague and notices a horseshoe hanging on the wall above the entrance. 'Do you really believe that a horseshoe brings luck?' he asks. 'No,' replies the colleague, 'but I've been told that it works even if you don't believe in it.'