One factor that has remained constant through all the twists and turns of the history of physical science is the decisive importance of the mathematical imagination.

I like people who are working on practical things and who are working in teams. It's not so important to get the glory. It's much more important to get something that works. It's a better way to live.

I think we're doing pretty well. It's clear the media, of course, always gives you the bad news.

From my childhood it has been my conviction that men would reach the planets in my lifetime . . . this conviction . . . rests on two beliefs, one scientific and one political: (1) there are more things in heaven and earth than are dreamed of in our present-day science. And we shall only find out what they are if we go out and look for them. (2) it is in the long run essential to the growth of any new and high civilization that small groups of people can escape from their neighbors and from their governments, to go and live as they please in the wilderness.

We simply don't know yet what's going to happen to the carbon in the atmosphere.

I'm a mathematician, basically. What I do is look around for problems where I can find useful applications for mathematics. All I do, really, is the math, and other people have the ideas.

A good cause can become bad if we fight for it with means that are indiscriminately murderous. A bad cause can become good if enough people fight for it in a spirit of comradeship and self-sacrifice. In the end it is how you fight, as much as why you fight, that makes your cause good or bad.