They must often change, who would be constant in happiness or wisdom. Those who continually search for happiness will never find it. Happiness is made, not found. To be without some of the things you want is an indispensable part of happiness.

Understanding human nature must be the basis of any real improvement in human life. Science has done wonders in mastering the laws of the physical world, but our own nature is much less understood, as yet, than the nature of stars and electrons. When science learns to understand human nature, it will be able to bring a happiness into our lives which machines and the physical sciences have failed to create.

All great books contain boring portions, and all great lives have contained uninteresting stretches.

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

The human race may well become extinct before the end of the century. Speaking as a mathematician, I should say the odds are about three to one against survival.

I am as drunk as a lord, but then, I am one, so what does it matter ?

There is exactly the same degree of possibility and likelihood of the existence of the Christian God as there is of the existence of the Homeric god. I cannot prove that either the Christian god or the Homeric gods do not exist, but I do not think that their existence is an alternative that is sufficiently probable to be worth serious consideration.