Speak only if it improves upon the silence.

Life is like riding a bicycle. To keep your balance you must keep moving.

Try to become not a man of success, but try rather to become a man of value.

The world is a dangerous place to live, not because of the people who are evil, but because of the people who don't do anything about it.

The secret to creativity is knowing how to hide your sources.

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution.

I'm not an atheist and I don't think I can call myself a pantheist. We are in the position of a little child entering a huge library filled with books in many different languages. The child knows someone must have written those books. It does not know how. The child dimly suspects a mysterious order in the arrangement of the books but doesn't know what it is. That, it seems to me, is the attitude of even the most intelligent human being toward God.

I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. Letter to Harry S. Truman.

Reality is merely an illusion, albeit a very persistent one.

Science without religion is lame, religion without science is blind.