Commentaria in Summam contra Gentiles, Liber III

Thirdly, ¹ it is shown that man's ultimate happiness is not in the act of prudence either, as Diogenes the Cynic and the Stoics maintained; although active and civic happiness is in it, as was stated in the preceding chapter ² according to the mind of Aristotle.

I. And it is argued first: because the act of prudence is only about the matters of the moral virtues, in which man's ultimate happiness does not consist ³.

Secondly. Because man's ultimate happiness is in man's best operation, which is about the most perfect objects.

Now, the operation of prudence is not about the most noble objects of the intellect or reason, since it is only about contingent things.

Thirdly. Because the act of prudence is ordered to something else as to an end: both because it is practical knowledge, and because prudence makes a man well-disposed in those things that are for the sake of the end, as is clear in Ethics VI.

Fourthly. Because brute animals share something of prudence, as is clear in Metaphysics I; but they share nothing of happiness, as is shown in Ethics I.

II. Concerning the first argument, it should be noted, from the teaching of St. Thomas in Ia-IIae, q. 58, a. 3, ad 1; in III, d. 23, q. 1, a. 4, qa. 2, ad 3; and De Virt. Cardin., a. 1, ad 3, that prudence is midway between the intellectual and the moral virtues: for according to its essence and subject it is an intellectual virtue, but according to its matter it is moral, since it is the right reason of things to be done, and is directive of the moral virtues. Therefore it is said here that the act of prudence is only about the matters of the moral virtues, namely, as about its matter.

2. Concerning the second argument, it should be noted, from St. Thomas in Ia-IIae, q. 57, a. 4, ad 2; and a. 5, ad 3; and IIa-IIae, q. 47, a. 5; and it is according to the mind of Aristotle in Ethics VI ⁴, that although prudence and art are among the number of the intellectual virtues according to essence and according to subject, they are nonetheless distinguished from speculative intellectual habits, because the latter are about necessary things, whereas the former are about contingent things that can be otherwise: for art is about things to be made, namely, those that pass over into external matter, while prudence is about things to be done, namely, operations that are immanent in the agent; for it is the regulator and governor of human choices, and choice follows the judgment of reason concerning things to be done, which judgment is about contingent things, as is stated in Ia-IIae, q. 13, a. 6, ad 2. Therefore it is well said here that prudence is about contingent things.

3. Concerning the third argument, it should be noted, from the teaching of St. Thomas in De Veritate, q. 5, a. 1, that, since two things are to be considered in things to be done, namely, the end, and those things that are for the sake of the end, the moral virtues cause the affection and good disposition toward the end, whereas prudence directs in those things that are for the sake of the end, inasmuch as it directs counsel and choice, which are about those things that are for the sake of the end. Therefore it is said here that prudence makes a man well-disposed in those things that are for the sake of the end.

4. Concerning the fourth argument, it should be observed that brute animals are said to share something of prudence, not because the virtue of prudence is in them in any way, since reason is not in them, while prudence is the right reason of things to be done, as is said in Ethics VI, ⁵ but because in their works they are moved in a manner similar to that in which a prudent person operates. For just as a prudent person proceeds in an orderly way in his works, as deliberating from reason about what he ought to do, so brute animals, as St. Thomas says in Ia-IIae, q. 13, a. 2, ad 3, and in Metaph. I, ⁶ are inclined by natural instinct toward certain most ordered operations, as being directed by divine art. Hence prudence in them is said to be a kind of natural estimation concerning pursuing what is fitting and fleeing what is harmful, but not a knowledge by which, with deliberation, one thing ordered to an end is judged to be chosen before another, which properly belongs to reason.