Book 6: The Intellectual Virtues.
But here an objection may be raised. “What is the use of them?” it may be asked. “Wisdom does not consider what tends to make man happy (for it does not ask how anything is brought about). Prudence indeed does this, but why do we need it? Prudence is the faculty which deals with what is just and noble and good for man, i.e. with those things which it is the part of the good man to do; but the knowledge of them no more makes us apter to do them, if (as has been said) the [moral] virtues are habits, than it does in the case of what is healthy and wholesome—healthy and wholesome, that is, not in the sense of conducing to, but in the sense of issuing from, a healthy habit; for a knowledge of medicine and gymnastics does not make us more able to do these things.
“But if it be meant that a man should be prudent, not in order that he may do these acts, but in order that he may become able to do them, then prudence will be no use to those who are good, nor even to those who are not. For it will not matter whether they have prudence themselves, or take the advice of others who have it. It will be enough to do in these matters as we do in regard to health; for if we wish to be in health, we do not go and learn medicine.
“Again, it seems to be a strange thing that prudence, though inferior to wisdom, must yet govern it, since in every field the practical faculty bears sway and issues orders.”
We must now discuss these points; for hitherto we have been only stating objections.
First, then, we may say that both prudence and wisdom must be desirable in themselves, since each is the virtue of one of the parts of the soul, even if neither of them produces anything.
Next, they do produce something.
On the one hand, wisdom produces happiness, not in the sense in which medicine produces health, but in the sense in which health produces health; that is to say, wisdom being a part of complete virtue, its possession and exercise make a man happy.
On the other hand [in the sphere of action], man performs his function perfectly when he acts in accordance with both prudence and moral virtue; for while the latter ensures the rightness of the end aimed at, the former ensures the rightness of the means thereto.
The fourth part of the soul, the vegetative part, or the faculty of nutrition, has no analogous excellence; for it has no power to act or not to act.
But as to the objection that prudence makes us no more apt to do what is noble and just, let us take the matter a little deeper, beginning thus:—
We allow, on the one hand, that some who do just acts are not yet just; e.g. those who do what the laws enjoin either unwillingly or unwittingly, or for some external motive and not for the sake of the acts themselves (though they do that which they ought and all that a good man should do). And, on the other hand, it seems that when a man does the several acts with a certain disposition he is good; i.e. when he does them of deliberate purpose, and for the sake of the acts themselves.
Now, the rightness of the purpose is secured by [moral] virtue, but to decide what is proper to be done in order to carry out the purpose belongs not to [moral] virtue, but to another faculty. But we must dwell a little on this point and try to make it quite clear.
There is a faculty which we call cleverness (δεινότης)—the power of carrying out the means to any proposed end, and so achieving it. If then the end be noble, the power merits praise; but if the end be base, the power is the power of the villain. So we apply the term clever both to the prudent man and the villain.
Now, this power is not identical with prudence, but is its necessary condition. But this power, the “eye of the soul” as we may call it, does not attain its perfect development without moral virtue, as we said before, and as may be shown thus:—
All syllogisms or deductive reasonings about what is to be done have for their starting point [principle or major premise] “the end or the supreme good is so and so” (whatever it be; any definition of the good will do for the argument). But it is only to the good man that this presents itself as the good; for vice perverts us and causes us to err about the principles of action. So it is plain, as we said, that it is impossible to be prudent without being morally good.