All history teaches us that these questions that we think the pressing ones will be transmuted before they are answered, that they will be replaced by others, and that the very process of discovery will shatter the concepts that we today use to describe our puzzlement.

If we must live with a perpetual sense that the world and the men in it are greater than we and too much for us, let it be the measure of our virtue that we know this and seek no comfort.

I can't think that it would be terrible of me to say - and it is occasionally true - that I need physics more than friends.

If atomic bombs are to be added as new weapons to the arsenals of a warring world, or to the arsenals of nations preparing for war, then the time will come when mankind will curse the names of Los Alamos and Hiroshima. The people must unite or they will perish.

Pragmatism is an intellectually safe but ultimately sterile philosophy.

Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search.

Sometimes the answer to fear does not lie in trying to explain away the causes, sometimes the answer lies in courage.