The most savage controversies are about matters as to which there is no good evidence either way.

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

If we were all given by magic the power to read each other’s thoughts, I suppose the first effect would be almost all friendships would be dissolved; the second effect, however, might be excellent, for a world without any friends would be felt to be intolerable, and we should learn to like each other without needing a veil of illusion to conceal from ourselves that we did not think each other absolutely perfect.

My sad conviction is that people can only agree about what they're not really interested in.

Men have physical needs, and they have emotions. While physical needs are unsatisfied, they take first place; but when they are satisfied, emotions unconnected with them become important in deciding whether a man is to be happy or unhappy.

A man is rational in proportion as his intelligence informs and controls his desires.

Hitler is an outcome of Rousseau.