Everything we call real is made of things that cannot be regarded as real.

An expert is a man who has made all the mistakes which can be made, in a narrow field.

Prediction is very difficult, especially if it's about the future.

If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet.

Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it.

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 are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. My own feeling is that it is not crazy enough.

It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we say about Nature.

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

Einstein, stop telling God what to do!

There are trivial truths and the great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true.

Never express yourself more clearly than you are able to think.

Every sentence I utter must be understood not as an affirmation, but as a question.

If anybody says he can think about quantum physics without getting giddy, that only shows he has not understood the first thing about them.

No, no, you're not thinking; you're just being logical.

The opposite of a fact is falsehood, but the opposite of one profound truth may very well be another profound truth.

When it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images.

A physicist is just an atom's way of looking at itself.

How wonderful that we have met with a paradox. Now we have some hope of making progress.