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.

When conscious activity is wholly concentrated on some one definite purpose, the ultimate result, for most people, is lack of balance accompanied by some form of nervous disorder.

Love should be a tree whose roots are deep in the earth, but whose branches extend into heaven.

Do not feel certain of anything.

We do not like to be robbed of an enemy; we want someone to hate when we suffer. It is so depressing to think that we suffer because we are fools; yet, taking mankind in the mass, that is the truth.

To discover a system for the avoidance of war is a vital need of our civilisation.

Ants and savages put strangers to death.