Aristotle, Nicomachean Ethics
H. Rackham, Ed.

for it does not ask how anything comes into existence. Prudence, it must be granted, does do this; but what do we need it for? seeing that it studies that which is just and noble and good for man, but these are the things that a good man does by nature. Knowing about them does not make us any more capable of doing them, since the virtues are qualities of character; just as is the case with the knowledge of what is healthy and vigorous—using these words to mean not productive of health and vigor but resulting from them: we are not rendered any more capable of healthy and vigorous action by knowing the science of medicine or of physical training. [2]

If on the other hand we are to say that Prudence is useful not in helping us to act virtuously but in helping us to become virtuous, then it is of no use to those who are virtuous already. Nor is it of any use either to those who are not, since we may just as well take the advice of others who possess Prudence as possess Prudence ourselves. We may be content to do as we do in regard to our health; we want to be healthy, yet we do not learn medicine. [3]

Moreover it would seem strange if Prudence, which is inferior to Wisdom, is nevertheless to have greater authority than Wisdom: yet the faculty that creates a thing¹ governs and gives orders to it.

Let us now therefore discuss these difficulties, which so far have only been stated.