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

Coincidence is God's way of remaining anonymous.

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

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.

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.

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

Physical concepts are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world. In our endeavor to understand reality we are somewhat like a man trying to understand the mechanism of a closed watch. He sees the face and the moving hands, even hears its ticking, but he has no way of opening the case. If he is ingenious he may form some picture of a mechanism which could be responsible for all the things he observes, but he may never be quite sure his picture is the only one which could explain his observations. He will never be able to compare his picture with the real mechanism and he cannot even imagine the possibility or the meaning of such a comparison.

Falling in love is not at all the most stupid thing that people do — but gravitation cannot be held responsible for it. Jotted (in German) on the margins of a letter to him (1933).

Subtle is the Lord, but malicious He is not.

The idea of achieving security through national armament is, at the present state of military technique, a disastrous illusion.

Now he has departed from this strange world a little ahead of me. That means nothing. People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion. Letter to the family of his lifelong friend Michele Besso, after learning of his death, (March 1955).