The fact that a belief has a good moral effect upon a man is no evidence whatsoever in favor of its truth. I'm not contending in a dogmatic way that there is not a God. What I'm contending is that we don't know that there is. I don't like the word "absolute." I don't think there is anything absolute whatever. The moral law, for example, is always changing. At one period in the development of the human race, almost everybody thought cannibalism was a duty.

What will be the good of the conquest of leisure and health, if no one remembers how to use them?

Every living thing is a sort of imperialist, seeking to transform as much as possible of its environment into itself.

It is not by delusion, however exalted, that mankind can prosper, but only by unswerving courage in the pursuit of truth.

I have sought love, first, because it brings ecstasy – ecstasy so great that I would often have sacrificed all the rest of life for a few hours of that joy. ... I have sought it, finally, because in the union of love I have seen, in a mystic miniature, the prefiguring vision of the heaven that saints and poets have imagined.

The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd.

In considering irregular appearances, there are certain very natural mistakes which must be avoided.