Whether science-and indeed civilization in general-can long survive depends upon psychology, that is to say, it depends upon what human beings desire.

My whole religion is this: do every duty, and expect no reward for it, either here or hereafter.

Either man will abolish war, or war will abolish man.

I think periods of browsing during which no occupation is imposed from without are important in youth because they give time for the formation of these apparently fugitive but really vital impressions.

Neither a man nor a crowd nor a nation can be trusted to act humanely or to think sanely under the influence of a great fear.

What Galileo and Newton were to the seventeenth century, Darwin was to the nineteenth.

I do not believe that I am now dreaming, but I cannot prove that I am not.