It has been shown that there are two kinds of virtue — intellectual and moral. Intellectual virtue is the result of learning. Moral virtue, on the other hand, comes about as the result of habit and practice. This shows that the moral virtues are not implanted in man by nature, for nothing created by nature can be made to change its direction or tendency by habit, nor are the moral virtues produced in man against nature. Man is not born either moral or immoral, but he has the capacity to develop moral virtue and this capacity can only be developed through habituation.
The development of moral excellence is not comparable to the development of other human capabilities. All men are endowed with certain faculties by nature. The ability to use these faculties is acquired before they are actually used (e.g., man has the ability to see before he sees, he has the ability to hear before he hears). The moral virtues, though, are acquired only by exercising them, just as skill in the arts and crafts is acquired only through use. For example, just as men become builders by building and harpists by playing the harp, so they become just by performing just actions and temperate by exercising self-control. This view is corroborated by what can be observed in any political system. Legislators seek to make good men of their citizens by making good behavior habitual through good laws. It is success or failure in this area that makes the difference between a good and a bad constitution.
