The first principle is that you must not fool yourself and you are the easiest person to fool.

[B]eyond poverty, beyond the point that the material needs are reasonably satisfied, only from within is peace.

So, ultimately, in order to understand nature it may be necessary to have a deeper understanding of mathematical relationships. But the real reason is that the subject is enjoyable, and although we humans cut nature up in different ways, and we have different courses in different departments, such compartmentaliz ation is really artificial, and we should take our intellectual pleasures where we find them.

I don't believe I can really do without teaching. The reason is, I have to have something so that when I don't have any ideas and I'm not getting anywhere, I can say to myself, "At least I'm living; at least I'm doing something. I'm making some contribution." It's just psychological.

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

Victory usually goes to those green enough to underestimate the monumental hurdles they are facing.

No one really understands quantum mechanics.