Abstract
MORAL virtues, as described in Aristotle's Nicomachean Ethics, bear certain important similarities to such human capacities as knowledge of medicine or artistic skill, as described in the Metaphysics. First, all of these qualities must be developed from inborn capacities, such as the senses. Whereas people are born with the capacities of vision and touch, they must acquire the abilities to use geometrical theorems, build houses, or act courageously. Second, both sorts of qualities--skills or knowledge on the one hand, virtue on the other--are manifested in action. Aristotle treats knowledge and art as types of potentialities in Metaphysics IX, where he defines them by reference to the actions in which they are realized. Virtues, too, are fully manifested in actions; Aristotle never tires of stressing the superiority of the person who actualizes his virtue in use.