'You thought, as a boy, that a mage is one who can do anything. So I thought once. So did we all. And the truth is that that as a man’s real power grows and his knowledge widens, ever the way he can follow grows narrower until at last he chooses nothing, but does only and wholly what he must do.'
- Master Summoner, in A Wizard of Earthsea by Ursula Le Guin.