If the world does not please you, you can change it.

There is no remorse like a remorse of chess. It is a curse upon man. There is no happiness in chess.

You cannot imagine the craving for rest that I feel-a hunger and thirst. For six long days, since my work was done, my mind has been a whirlpool, swift, unprogressive and incessant, a torrent of thoughts leading nowhere, spinning round swift and steady.

Biologists can be just as sensitive to heresy as theologians.

Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us.

Our challenge is not to educate the children we used to have or want to have, but to educate the children who come to the schoolhouse door.

Why had we come to the moon? The thing presented itself to me as a perplexing problem. What is this spirit in man that urges him for ever to depart from happiness and security, to toil, to place himself in danger, to risk an even a reasonable certainty of death? It dawned upon me that there in the moon as a thing I ought always to have known, that man is not made to go about safe and comfortable and well fed and amused. ... against his interest, against his happiness, he is constantly being driven to do unreasonable things. Some force not himself impels him, and he must go.