When two men of science disagree, they do not invoke the secular arm; they wait for further evidence to decide the issue, because, as men of science, they know that neither is infallible. But when two theologians differ, since there is no criteria to which either can appeal, there is nothing for it but mutual hatred and an open or covert appeal to force.

I think it would be just to say the most essential characteristic of mind is memory, using this word in its broadest sense to include every influence of past experience on present reactions.

It seems to us unwise to have insisted on teaching geometry to the younger Dionysius, tyrant of Syracuse, in order to make him a good king, but from Plato's point of view it was essential. He was sufficiently Pythagorean to think that without mathematics no true wisdom is possible.

Few people can be happy unless they hate some other person, nation, or creed.

An Honest politician will not be tolerated by a democracy unless he is very stupid ... because only a very stupid man can honestly share the prejudices of more than half the nation.

Science is what we know, and philosophy is what we don't know.

My own view on religion is . . . It helped in early days to fix the calendar, and . . . to chronicle eclipses . . . These two services I am prepared to acknowledge.