The desire to understand the world and the desire to reform it are the two great engines of progress, without which human society would stand still or retrogress.

...the nonexistence of God makes more difference to some of us than to others. To me, it means that there is no absolute morality, that moralities are sets of social conventions devised by humans to satisfy their needs.

Among the Tibetans, one wife has many husbands, because men are too poor to support a whole wife.

The skill of the politician consists in guessing what people can be brought to think advantageous to themselves; the skill of the expert consists in calculating what really is advantageous, provided people can be brought to think so.

One is often told that it is a very wrong thing to attack religion, because religion makes men virtuous. So I am told; I have not noticed it.

Aristotle, in spite of his reputation, is full of absurdities. He says that children should be conceived in the Winter, when the wind is in the North, and that if people marry too young the children will be female. He tells us that the blood of females is blacker than that of males; that the pig is the only animal liable to measles; that an elephant suffering from insomnia should have its shoulders rubbed with salt, olive-oil, and warm water; that women have fewer teeth than men, and so on. Nevertheless, he is considered by the great majority of philosophers a paragon of wisdom.

The pure mathematician, like the musician, is a free creator of his world of ordered beauty.