Gregorius dicit, in XXII Moral., quod "ceterae virtutes, nisi ea quae appetunt, prudenter agant, virtutes esse nequaquam possunt" quia inclinatio virtutis moralis est cum electione, et ideo ad suam perfectionem indiget quod sit ratio perfecta per virtutem intellectualem.
Gregory says (Moral. xxii) that "the other virtues, unless we do prudently what we desire to do, cannot be real virtues" because the inclination of moral virtue is with choice: and consequently in order that it may be perfect it requires that reason be perfected by intellectual virtue.
Naturalis inclinatio ad bonum virtutis, est quaedam inchoatio virtutis, non autem est virtus perfecta. Huiusmodi enim inclinatio, quanto est fortior, tanto potest esse periculosior, nisi recta ratio adiungatur, per quam fiat recta electio eorum quae conveniunt ad debitum finem, sicut equus currens, si sit caecus, tanto fortius impingit et laeditur, quanto fortius currit.
The natural inclination to a good of virtue is a kind of beginning of virtue, but is not perfect virtue. For the stronger this inclination is, the more perilous may it prove to be, unless it be accompanied by right reason, which rectifies the choice of fitting means towards the due end. Thus if a running horse be blind, the faster it runs the more heavily will it fall, and the more grievously will it be hurt.
Et ideo, etsi virtus moralis non sit ratio recta, ut Socrates dicebat, non tamen solum est secundum rationem rectam, inquantum inclinat ad id quod est secundum rationem rectam, ut Platonici posuerunt, sed etiam oportet quod sit cum ratione recta, ut Aristoteles dicit, in VI Ethic.
And consequently, although moral virtue be not right reason, as Socrates held, yet not only is it "according to right reason," insofar as it inclines man to that which is, according to right reason, as the Platonists maintained [Cf. Plato, Meno xli.], but also it needs to be "joined with right reason," as Aristotle declares (Ethic. vi, 13).
Virtus moralis potest quidem esse sine quibusdam intellectualibus virtutibus, sicut sine sapientia, scientia et arte, non autem potest esse sine intellectu et prudentia.
Moral virtue can be without some of the intellectual virtues, viz. wisdom, science, and art; but not without understanding and prudence.
Sine prudentia quidem esse non potest moralis virtus, quia moralis virtus est habitus electivus, idest faciens bonam electionem. Ad hoc autem quod electio sit bona, duo requiruntur.
Moral virtue cannot be without prudence, because it is a habit of choosing, i.e. making us choose well. Now in order that a choice be good, two things are required.
Primo, ut sit debita intentio finis, et hoc fit per virtutem moralem, quae vim appetitivam inclinat ad bonum conveniens rationi, quod est finis debitus.
First, that the intention be directed to a due end; and this is done by moral virtue, which inclines the appetitive faculty to the good that is in accord with reason, which is a due end.
Secundo, ut homo recte accipiat ea quae sunt ad finem, et hoc non potest esse nisi per rationem recte consiliantem, iudicantem et praecipientem; quod pertinet ad prudentiam et ad virtutes sibi annexas, ut supra dictum est.
Secondly, that man take rightly those things which have reference to the end: and this he cannot do unless his reason counsel, judge and command aright, which is the function of prudence and the virtues annexed to it, as stated above (q57 aa5,6).
Unde virtus moralis sine prudentia esse non potest, et per consequens nec sine intellectu. Per intellectum enim cognoscuntur principia naturaliter nota, tam in speculativis quam in operativis.
Wherefore there can be no moral virtue without prudence, and consequently neither can there be without understanding. For it is by the virtue of understanding that we know self-evident principles both in speculative and in practical matters.
Unde sicut recta ratio in speculativis, inquantum procedit ex principiis naturaliter cognitis, praesupponit intellectum principiorum, ita etiam prudentia, quae est recta ratio agibilium.
Consequently just as right reason in speculative matters, insofar as it proceeds from naturally known principles, presupposes the understanding of those principles, so also does prudence, which is the right reason about things to be done.