At least once a day, allow yourself the freedom to think and dream for yourself.

My interest in science was always essentially limited to the study of principles.... That I have published so little is due to this same circumstance, as the great need to grasp principles has caused me to spend most of my time on fruitless pursuits.

Since I do not forsee that atomic energy is to be a great boon for a long time, I have to say that for the present it is a menace. Perhaps it is well that it should be. It may intimidate the human race into bringing order into its international affairs, which, without the presence of fear, it would not do.

The dog is very smart. He feels sorry for me because I receive so much mail; that's why he tries to bite the mailman.

Is it not better for a man to die for a cause in which he believes, such as peace, than to suffer for a cause in which he does not believe, such as war?

If you're not sure why you're doing something, you can never do enough of it. Imagination is more important than knowledge.

Solitude is painful when one is young, but delightful when one is more mature.