Science, by itself, cannot supply us with an ethic. It can show us how to achieve a given end, and it may show us that some ends cannot be achieved. But among ends that can be achieved our choice must be decided by other than purely scientific considerations. If a man were to say, "I hate the human race, and I think it would be a good thing if it were exterminated," we could say, "Well, my dear sir, let us begin the process with you." But this is hardly argument, and no amount of science could prove such a man mistaken.

The taboo against nakedness is an obstacle to a decent attitude on the subject of sex.

The thing that I should wish to obtain from money would be leisure with security.

Man can be stimulated by hope or driven by fear, but the hope and the fear must be vivid and immediate if they are to be effective without producing weariness.

You may reasonably expect a man to walk a tightrope safely for ten minutes; it would be unreasonable to do so without accident for two hundred years.

I believe that the abolition of private ownership of land and capital is a necessary step toward any world in which the nations are to live at peace with one another.

Men fear thought as they fear nothing else on earth - more than ruin, more even than death.