Philosophus distinguit prudentiam ab arte, in VI Ethic, quia ars facit solum facultatem boni operis, quia non respicit appetitum; prudentia autem non solum facit boni operis facultatem, sed etiam usum: respicit enim appetitum, tanquam praesupponens rectitudinem appetitus.
The Philosopher distinguishes prudence from art (Ethic. vi, 5) because art confers the mere aptness for good work, since it does not regard the appetite; whereas prudence confers not only aptness for a good work, but also the use: for it regards the appetite, since it presupposes the rectitude thereof.
Ars est recta ratio factibilium; prudentia vero est recta ratio agibilium.
Art is the "right aspect of things to be made"; whereas prudence is the "right aspect of things to be done".
Diversa genera artificialium omnia sunt extra hominem: et ideo non diversificatur ratio virtutis. Sed prudentia est recta ratio ipsorum actuum humanorum: unde diversificatur ratio virtutis.
The various kinds of things made by art are all external to man: hence they are not constituted by a different formal aspect of virtue. But prudence correctly sees the formal aspect about human acts themselves: hence it is constituted by a unique formal aspect of virtue.
Prudentia est bene consiliativa de his quae pertinent ad totam vitam hominis, et ad ultimum finem vitae humanae. Sed in artibus aliquibus est consilium de his quae pertinent ad fines proprios illarum artium. Unde aliqui, inquantum sunt bene consiliativi in rebus bellicis vel nauticis, dicuntur prudentes duces vel gubernatores, non autem prudentes simpliciter: sed illi solum qui bene consiliantur de his quae conferunt ad totam vitam.
Prudence is of good counsel about matters regarding man's entire life, and the end of human life. But in some arts there is counsel about matters concerning the ends proper to those arts. Hence some men, in so far as they are good counselors in matters of warfare, or seamanship, are said to be prudent officers or pilots, but not simply prudent: only those are simply prudent who give good counsel about all the concerns of life.
Perfectio autem et rectitudo rationis, in speculativis, dependet ex principiis, ex quibus ratio syllogizat; sicut dictum est quod scientia dependet ab intellectu, qui est habitus principiorum, et praesupponit ipsum. In humanis autem actibus se habent fines sicut principia in speculativis, ut dicitur in VII Ethic.
Perfection and rectitude of aspect, in speculative matters, depends on principles, by which the formal aspect structures syllogisms; thus we have said above (q57 a2 ad 2) that science depends on understanding, which is the habit of principles, and presupposes it. But in human acts, the ends stand as the principles do in speculative matters, as stated in Ethic. vii, 8.
Et ideo ad prudentiam, quae est recta ratio agibilium, requiritur quod homo sit bene dispositus circa fines: quod quidem est per appetitum rectum. Et ideo ad prudentiam requiritur moralis virtus, per quam fit appetitus rectus.
Consequently, it is requisite for prudence, which is right aspect about things to be done, that man be well disposed with regard to the ends: and this depends on the rectitude of his appetite. Wherefore, for prudence there is need of moral virtue, which rectifies the appetite.