If the professors of English will complain to me that the students who come to the universities, after all those years of study, still cannot spell 'friend,' I say to them that something's the matter with the way you spell friend.

Listen, I mean that from my knowledge of the world that I see around me, I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence.

The real question of government versus private enterprise is argued on too philosophical and abstract a basis. Theoretically, planning may be good. But nobody has ever figured out the cause of government stupidity—and until they do (and find the cure), all ideal plans will fall into quicksand.

The test of all knowledge is experiment. Experiment is the sole judge of scientific truth.

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.

It is necessary for the very existence of science that minds exist which do not allow that nature must satisfy some preconceived conditions.

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.