My rule is, when you are unhappy, think about it. But when you're happy, don't. Why spoil it? You're probably happy for some ridiculous reason and you'd just spoil it to know it.

Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question - to doubt - to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

To test whether you have learned an idea or a definition, rephrase what you just learned without using the new word.

To guess what to keep and what to throw away takes considerable skill. Actually it is probably merely a matter of luck, but it looks as if it takes considerable skill.

I think I can safely say that nobody understands Quantum Mechanics.

I love to think. I once considered taking drugs as an attempt to better understand an altered state of mind; however, I decided not to. I didn't want to chance ruining the machine.

In a way, the Nobel Prize has been something of a pain in the neck, though there was at least one time that I got some fun out of it, Shortly after I won the Prize, Gweneth and I received an invitation from the Brazilian government to be the guests of honor at the Carnaval celebrations in Rio.