If you want to live a happy life, tie it to a goal, not to people or things.

In the middle of difficulty lies opportunity.

When you sit with a nice girl for two hours you think it's only a minute. But when you sit on a hot stove for a minute you think it's two hours. That's relativity.

Only a life lived for others is the life worth while.

There exists a passion for comprehension, just as there exists a passion for music. That passion is rather common in children, but gets lost in most people later on. Without this passion there would be neither mathematics nor natural science.

The real problem is in the hearts and minds of men. It is not a problem of physics but of ethics. It is easier to denature plutonium than to denature the evil spirit of man.

Teaching should be such that what is offered is perceived as a valuable gift and not as a hard duty.

When I was young, I found out that the big toe always ends up making a hole in the sock. So I stopped wearing socks.

Imagination is more important than knowledge.

I believe serious progress (in the abolition of war) can be achieved only when men become organized on an international scale and refuse, as a body, to enter military or war service.