Three great forces rule the world: stupidity, fear and greed.

Certainly there are things worth believing. I believe in the brotherhood of man and the uniqueness of the individual. But if you ask me to prove what I believe, I can't. You know them to be true but you could spend a whole lifetime without being able to prove them. The mind can proceed only so far upon what it knows and can prove. There comes a point where the mind takes a leap—call it intuition or what you will—and comes out upon a higher plane of knowledge, but can never prove how it got there. All great discoveries have involved such a leap.

Pure mathematics is, in its way, the poetry of logical ideas.

We have to do the best we are capable of. This is our sacred human responsibility.

To invent something, all you need is imagination and a big pile of junk.

The hardest thing to understand in the world is the income tax.

The only sure way to avoid making mistakes is to have no new ideas.