“If I had known they were going to do this, I would have become a shoemaker.”

“If I had only known, I would have been a locksmith. ”

“The release of atomic power has changed everything except our way of thinking ... the solution to this problem lies in the heart of mankind. If only I had known, I should have become a watchmaker. (1945)”

“I want to go when I want. It is tasteless to prolong life artificially. I have done my share, it is time to go. I will do it elegantly.”

“When I am judging a theory, I ask myself whether, if I were God, I would have arranged the world in such a way.”

“If I were not a Jew I would be a Quaker.”

“If we knew what it was we were doing, it would not be called research, would it?”