I want to know what God thinks. The rest are details.

One of the strongest motives that lead men to art and science is escape from everyday life with its painful crudity and hopeless dreariness, from the fetters of one's own ever-shifting desires. A finely tempered nature longs to escape from the personal life into the world of objective perception and thought.

We come now to the question: what is a priori certain or necessary, respectively in geometry (doctrine of space) or its foundations? Formerly we thought everything; nowadays we think nothing. Already the distance-concept is logically arbitrary; there need be no things that correspond to it, even approximately.

The only mistake in life is the lesson not learned.

[Max Planck] was one of the finest people I have ever known... but he really didn't understand physics, [because] during the eclipse of 1919 he stayed up all night to see if it would confirm the bending of light by the gravitational field. If he had really understood [general relativity], he would have gone to bed the way I did

But love brings much happiness - much more so than pining brings pain.

Innovation is not the product of logical thought, even though the final product is tied to a logical structure.