It is the same with people as it is with riding a bike. Only when moving can one comfortably maintain one's balance.

Coincidences are God's way of staying anonymous.

Nobody knows how the stand of our knowledge about the atom would be without him. Personally, [Niels] Bohr is one of the amiable colleagues I have met. He utters his opinions like one perpetually groping and never like one who believes himself to be in possession of the truth.

Cherish the questions, for the answers keep changing.

Only a very dull man spells a word the same way twice.

I think and think for months and years. Ninety-nine times, the conclusion is false. The hundredth time I am right.

I sometimes ask myself how it came about that I was the one to develop the theory of relativity. The reason, I think, is that a normal adult never stops to think about problems of space and time. These are things which he has thought about as a child. Bu t my intellectual development was retarded,as a result of which I began to wonder about space and time only when I had already grown up.