You'll never have a quiet world till you knock the patriotism out of the human race.

The only person who acts sensibly is my tailor. He takes my measure anew every time he sees me. Everyone else goes by their old measurements.

The fact that a believer is happier than a skeptic is no more to the point than the fact that a drunken man is happier than a sober one.

I never climbed any ladder: I have achieved eminence by sheer gravitation.

You do not settle whether an argument is justified by merely showing that it is of some use. The distinction is not between useful and useless experiments but between barbarous and civilized behaviour. Vivisection is a social evil because if it advances human knowledge, it does so at the expense of human character.

Fashions, after all, are only induced epidemics.

Besides, do any of us understand what we are doing? If we did, would we ever do it?