When you are courting a nice girl an hour seems like a second.

Somebody who only reads newspapers and at best books of contemporary authors looks to me like an extremely near-sighted person who scorns eyeglasses. He is completely dependent on the prejudices and fashions of his times, since he never gets to see or hear anything else.

Dear Posterity, If you have not become more just, more peaceful, and in general more sensible... then may the Devil take you!

The world is so full of possibilities that dogmatism is simply indecent.

You can't solve problems with the same thinking that caused them.

Human beings, in their thinking, feeling and acting are not free agents but are as causally bound as the stars in their motion.

The theoretical idea ... does not arise apart from and independent of experience; nor can it be derived from experience by a purely logical procedure. It is produced by a creative act. Once a theoretical idea has been acquired, one does well to hold fast to it until it leads to an untenable conclusion.