It is only theory that makes men completely incautious.

It is obviously possible that what we call waking life may only be an unusual and persistent nightmare.

When I was a child . . . Only virtue was prized, virtue at the expense of intellect, health, happiness, and every mundane good.

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.

There can't be a practical reason for believing something that is not true.

A life which goes excessively against natural impulse is... likely to involve effects of strain that may be quite as bad as indulgence in forbidden impulses would have been. People who live a life which is unnatural beyond a point are likely to be filled with envy, malice and uncharitableness.

There is much pleasure to be gained from useless knowledge.