A clever person solves a problem. A wise person avoids it.

Coincidence is God's way of remaining anonymous.

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.

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

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.