Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That's relativity.

Speak only if it improves upon the silence.

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

Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life. Because almost everything — all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.

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

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

He who is not contented with what he has, would not be contented with what he would like to have.

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.

Wisdom is not a product of schooling but of the lifelong attempt to acquire it.