 When each of [the people of the excellent city] acts in this way [i.e., according to the citizens’ common duties], these actions of his make him acquire a good and excellent disposition of the soul, and the more steadily he applies himself to them, the stronger and better becomes that disposition of this and increases in strength and excellence—just as steadily applying himself to performing the actions of writing well make a man acquire proficiency in the art of writing …. (Perfect State V, 16, 2: 261)