Human behavior flows from three main sources: desire, emotion, and knowledge.

It is as expedient that a wicked man be punished as that a sick man be cured by a physician; for all chastisement is a kind of medicine.

I have hardly ever known a mathematician who was capable of reasoning.

For the man who makes everything that leads to happiness, or near to it, to depend upon himself, and not upon other men, on whose good or evil actions his own doings are compelled to hinge,--such a one, I say, has adopted the very best plan for living happily. This is the man of moderation; this is the man of manly character and of wisdom.

For the poets tell us, don't they, that the melodies they bring us are gathered from rills that run with honey, out of glens and gardens of the Muses, and they bring them as bees do honey, flying like the bees? And what they say is true, for a poet is a light and winged thing, and holy, and never able to compose until he has become inspired, and is beside himself, and reason is no longer in him. So long as he has this in his possession, no man is able to make poetry or to chant in prophecy.

...for the object of education is to teach us to love beauty.

So the nature required to make a really noble Guardian of our commonwealth will be swift and strong, spirited, and philosophic.