For me, science is just a bunch of tools - it's like playing the violin. I just enjoy calculating, and it's an instrument I know how to play. It's almost an athletic performance, in a way. I was just watching the Olympics, and that's how I feel when proving a theorem.

The thing that makes me most optimistic is China and India - both of them doing well. It's amazing how much progress there's been in China, and also India. Those are the places that really matter - they're half of the world's population. They're the places where things are enormously better now than they were 50 years ago. And I don't see anything that's going to stop that.

The technologies that raise the fewest ethical problems are those that work on a human scale, brightening the lives of individual people.

Science and religion are, of course, two different ways of looking at the universe; and it's the same universe with two different windows.

So long as you have courage and a sense of humor, it is never too late to start life afresh.

For a physicist mathematics is not just a tool by means of which phenomena can be calculated, it is the main source of concepts and principles by means of which new theories can be created.

Well germ warfare of course exists. There have been on a small scale... There have been, of course, a few people who got killed with anthrax right here in Princeton.