Aristotle, Nicomachean Ethics
H. Rackham, Ed.

13. We have therefore also to reconsider the nature of Virtue. The fact is that the case of Virtue is closely analogous to that of Prudence in relation to Cleverness. Prudence and Cleverness are not the same, but they are similar; and natural virtue is related in the same way to Virtue in the true sense. All are agreed that the various moral qualities are in a sense bestowed by nature: we are just, and capable of temperance, and brave, and possessed of the other virtues from the moment of our birth. But nevertheless we expect to find that true goodness is something different, and that the virtues in the true sense come to belong to us in another way. For even children and wild animals possess the natural dispositions, yet without Intelligence these may manifestly be harmful. This at all events appears to be a matter of observation, that just as a man of powerful frame who has lost his sight meets with heavy falls when he moves about, because he cannot see, so it also happens in the moral sphere; [2] whereas if a man of good natural disposition acquires Intelligence,¹ then he excels in conduct, and the disposition which previously only resembled Virtue will now be Virtue in the true sense. Hence just as with the faculty of forming opinions² there are two qualities, Cleverness and Prudence, so also in the moral part of the soul there are two qualities, natural virtue and true Virtue; and true Virtue cannot exist without Prudence. [3] Hence some people maintain that all the virtues are forms of Prudence; and Socrates' line of enquiry was right in one way though wrong in another; he was mistaken in thinking that all the virtues are forms of Prudence, but right in saying that they cannot exist without Prudence. [4] A proof of this is that everyone, even at the present day, in defining Virtue, after saying what disposition it is³ and specifying the things with which it is concerned, adds that it is a disposition determined by the right principle; and the right principle is the principle determined by Prudence. It appears therefore that everybody in some sense, divines that Virtue is a disposition of this nature, namely regulated by Prudence. [5] This formula however requires a slight modification. Virtue is not merely a disposition conforming to right principle, but one cooperating with right principle; and Prudence is right principle⁴ in matters of conduct. Socrates then thought that the virtues are principles, for he said that they are all of them forms of knowledge. We on the other hand say that the virtues cooperate with principle. [6]

These considerations therefore show that it is not possible to be good in the true sense without Prudence, nor to be prudent without Moral Virtue.

（Moreover, this might supply an answer to the dialectical argument that might be put forward to prove that the virtues can exist in isolation from each other, on the ground that the same man does not possess the greatest natural capacity for all of them, so that he may have already attained one when he has not yet attained another. In regard to the natural virtues this is possible; but it is not possible in regard to those virtues which entitle a man to be called good without qualification. For if a man have the one virtue of Prudence he will also have all the Moral Virtues together with it.） [7]

It is therefore clear⁵ that, even if Prudence had no bearing on conduct, it would still be needed, because it is the virtue of⁶ that part of the intellect to which it belongs; and also that our choice of actions will not be right without Prudence any more than without Moral Virtue, since, while Moral Virtue enables us to achieve⁷ the end, Prudence makes us adopt the right means to the end. [8]

But nevertheless it is not really the case that Prudence is in authority⁸ over Wisdom, or over the higher part of the intellect, any more than medical science is in authority over health. Medical science does not control health, but studies how to procure it; hence it issues orders in the interests of health, but not to health. And again, one might as well say that Political Science governs the gods, because it gives orders about everything⁹ in the State.