[Prudence] is the virtue of that part of the intellect [the calculative] to which it belongs; and . . . our choice of actions will not be right without Prudence any more than without Moral Virtue, since, while Moral Virtue enables us to achieve the end, Prudence makes us adopt the right means to the end.
AristotleIt is the active exercise of our faculties in conformity with virtue that causes happiness, and the opposite activities its opposite.
Aristotle