“If I could do it all again, I'd be a plumber.”

“I do not believe that civilization will be wiped out in a war fought with the atomic bomb. Perhaps two-thirds of the people of the Earth might be killed, but enough men capable of thinking, and enough books, would be left to start again, and civilization could be restored.”

“If I were to remain silent, I'd be guilty of complicity.”

“I feel compelled to say something else to you. There has been a certain ill-feeling between us the cause of which I do not want to analyze. I have struggled against the feeling of bitterness attached to it, with complete success. I think of you again with unmixed geniality and ask you to try to do the same with me. It is a shame when two real fellows who have extricated themselves somewhat from this shabby world do not afford each other mutual pleasure.”

“If I had an hour to solve a problem I'd spend 55 minutes thinking about the problem and 5 minutes thinking about solutions.”

“I'd rather be an optimist and a fool than a pessimist and right.”

“I am not more gifted than the average human being. If you know anything about history, you would know that is so--what hard times I had in studying and the fact that I do not have a memory like some other people do… I am just more curious than the average person and I will not give up on a problem until I have found the proper solution. This is one of my greatest satisfactions in life--solving problems--and the harder they are, the more satisfaction do I get out of them. Maybe you could consider me a bit more patient in continuing with my problem than is the average human being. Now, if you understand what I have just told you, you see that it is not a matter of being more gifted but a matter of being more curious and maybe more patient until you solve a problem.”