If there is something very slightly wrong in our definition of the theories, then the full mathematical rigor may convert these errors into ridiculous conclusions.

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.

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

Tell your son to stop trying to fill your head with science - for to fill your heart with love is enough!

During the Middle Ages there were all kinds of crazy ideas, such as that a piece of rhinoceros horn would increase potency. Then a method was discovered for separating the ideas - which was to try one to see if it worked, and if it didn't work, to eliminate it. This method became organized, of course, into science.

We are very lucky to be living in an age in which we are still making discoveries. It is like the discovery of America-you only discover it once. The age in which we live is the age in which we are discovering the fundamental laws of nature, and that day will never come again. It is very exciting, it is marvelous, but this excitement will have to go.

There is enough energy in a single cubic meter of space to boil all the oceans in the world.