"The future of mankind depends on the wisdom of its leaders. And that is a very frightening thought."

"I consider the idea of a personal God as being very childish. We must give up this idea."

"A theoretical science, if it is to be healthy, must be able to hold its own against the practical application of its theories."

"The world is a book, and those who do not travel read only one page."

"The quantum theory is an 'unpleasant' theory, which I should have liked to assume to be true only if I were forced to do so by the facts."