We need to teach how doubt is not to be feared but welcomed. It's OK to say, "I don't know."

Agnostic for me would be trying to weasel out and sound a little nicer than I am about this.

Nobody ever figures out what life is all about, and it doesn't matter. Explore the world. Nearly everything is really interesting if you go into it deeply enough.

The present situation in physics is as if we know chess, but we don't know one or two rules.

It does not make any difference how beautiful your guess is. It does not make any difference how smart you are, who made the guess, or what his name is if it disagrees with experiment it is wrong. That is all there is to it.

All the time you're saying to yourself, 'I could do that, but I won't,'--which is just another way of saying that you can't.

The basis of action on love, the brotherhood of all men, the value of the individual... the humility of the spirit.