How insidious Nature is when one is trying to get at it experimentally.

I'm more interested in the future than in the past, because the future is where I intend to live.

Education is not received. It is achieved.

[Kepler] had to realize clearly that logical-mathematical theoretizing, no matter how lucid, could not guarantee truth by itself; that the most beautiful logical theory means nothing in natural science without comparison with the exactest experience. Without this philosophic attitude, his work would not have been possible.

If you have never failed, you have never tried anything new.

When the Special Theory of Relativity began to germinate in me, I was visited by all sorts of nervous conflicts... I used to go away for weeks in a state of confusion.

It is every man's obligation to put back into the world at least the equivalent of what he takes out of it.