I answer that, The virtues must needs be connected together, so that whoever has one has all, as stated above (FS, Q[65], A[1]). Now whoever has grace has charity, so that he must needs have all the other virtues, and hence, since prudence is a virtue, as shown above (A[4]), he must, of necessity, have prudence also.
Reply to Objection 1: Diligence is twofold: one is merely sufficient with regard to things necessary for salvation; and such diligence is given to all who have grace, whom "His unction teacheth of all things" ( 1 Jn. 2:27 ). There is also another diligence which is more than sufficient, whereby a man is able to make provision both for himself and for others, not only in matters necessary for salvation, but also in all things relating to human life; and such diligence as this is not in all who have grace.
Reply to Objection 2: Those who require to be guided by the counsel of others, are able, if they have grace, to take counsel for themselves in this point at least, that they require the counsel of others and can discern good from evil counsel.
Reply to Objection 3: Acquired prudence is caused by the exercise of acts, wherefore "its acquisition demands experience and time" (Ethic. ii, 1), hence it cannot be in the young, neither in habit nor in act. On the other hand gratuitous prudence is caused by divine infusion. Wherefore, in children who have been baptized but have not come to the use of reason, there is prudence as to habit but not as to act, even as in idiots; whereas in those who have come to the use of reason, it is also as to act, with regard to things necessary for salvation. This by practice merits increase, until it becomes perfect, even as the other virtues. Hence the Apostle says ( Heb. 5:14 ) that "strong meat is for the perfect, for them who by custom have their senses exercised to the discerning of good and evil."
Whether prudence is in us by nature?
Objection 1: It would seem that prudence is in us by nature. The Philosopher says that things connected with prudence "seem to be natural," namely "synesis, gnome" [* and , Cf. FS, Q[57], A[6]] and the like, but not those which are connected with speculative wisdom. Now things belonging to the same genus have the same kind of origin. Therefore prudence also is in us from nature.
Objection 2: Further, the changes of age are according to nature. Now prudence results from age, according to Job 12:12 : "In the ancient is wisdom, and in length of days prudence." Therefore prudence is natural.
Objection 3: Further, prudence is more consistent with human nature than with that of dumb animals. Now there are instances of a certain natural prudence in dumb animals, according to the Philosopher (De Hist. Anim. viii, 1). Therefore prudence is natural.
On the contrary, The Philosopher says (Ethic. ii, 1) that "intellectual virtue is both originated and fostered by teaching; it therefore demands experience and time." Now prudence is an intellectual virtue, as stated above (A[4]). Therefore prudence is in us, not by nature, but by teaching and experience.
I answer that, As shown above (A[3]), prudence includes knowledge both of universals, and of the singular matters of action to which prudence applies the universal principles. Accordingly, as regards the knowledge of universals, the same is to be said of prudence as of speculative science, because the primary universal principles of either are known naturally, as shown above (A[6]): except that the common principles of prudence are more connatural to man; for as the Philosopher remarks (Ethic. x, 7) "the life which is according to the speculative reason is better than that which is according to man": whereas the secondary universal principles, whether of the speculative or of the practical reason, are not inherited from nature, but are acquired by discovery through experience, or through teaching.
On the other hand, as regards the knowledge of particulars which are the matter of action, we must make a further distinction, because this matter of action is either an end or the means to an end. Now the right ends of human life are fixed; wherefore there can be a natural inclination in respect of these ends; thus it has been stated above (FS, Q[51], A[1]; FS, Q[63], A[1]) that some, from a natural inclination, have certain virtues whereby they are inclined to right ends; and consequently they also have naturally a right judgment about such like ends.
But the means to the end, in human concerns, far from being fixed, are of manifold variety according to the variety of persons and affairs. Wherefore since the inclination of nature is ever to something fixed, the knowledge of those means cannot be in man naturally, although, by reason of his natural disposition, one man has a greater aptitude than another in discerning them, just as it happens with regard to the conclusions of speculative sciences. Since then prudence is not about the ends, but about the means, as stated above (A[6]; FS, Q[57], A[5]), it follows that prudence is not from nature.
Reply to Objection 1: The Philosopher is speaking there of things relating to prudence, in so far as they are directed to ends. Wherefore he had said before (Ethic. vi, 5,11) that "they are the principles of the " [*Literally, 'for the sake of which' (are the means)], namely, the end; and so he does not mention among them, because it takes counsel about the means.
Reply to Objection 2: Prudence is rather in the old, not only because their natural disposition calms the movement of the sensitive passions, but also because of their long experience.
Reply to Objection 3: Even in dumb animals there are fixed ways of obtaining an end, wherefore we observe that all the animals of a same species act in like manner. But this is impossible in man, on account of his reason, which takes cognizance of universals, and consequently extends to an infinity of singulars.
Whether prudence can be lost through forgetfulness?
Objection 1: It would seem that prudence can be lost through forgetfulness. For since science is about necessary things, it is more certain than prudence which is about contingent matters of action. But science is lost by forgetfulness. Much more therefore is prudence.
Objection 2: Further, as the Philosopher says (Ethic. ii, 3) "the same things, but by a contrary process, engender and corrupt virtue." Now the engendering of prudence requires experience which is made up "of many memories," as he states at the beginning of his Metaphysics (i, 1). Therefore since forgetfulness is contrary to memory, it seems that prudence can be lost through forgetfulness.
Objection 3: Further, there is no prudence without knowledge of universals. But knowledge of universals can be lost through forgetfulness. Therefore prudence can also.
On the contrary, The Philosopher says (Ethic. vi, 5) that "forgetfulness is possible to art but not to prudence."
I answer that, Forgetfulness regards knowledge only, wherefore one can forget art and science, so as to lose them altogether, because they belong to the reason. But prudence consists not in knowledge alone, but also in an act of the appetite, because as stated above (A[8]), its principal act is one of command, whereby a man applies the knowledge he has, to the purpose of appetition and operation. Hence prudence is not taken away directly by forgetfulness, but rather is corrupted by the passions. For the Philosopher says (Ethic. vi, 5) that "pleasure and sorrow pervert the estimate of prudence": wherefore it is written ( Dan. 13:56 ): "Beauty hath deceived thee, and lust hath subverted thy heart," and ( Ex. 23:8 ): "Neither shalt thou take bribes which blind even the prudent [Douay: 'wise']."
Nevertheless forgetfulness may hinder prudence, in so far as the latter's command depends on knowledge which may be forgotten.
Reply to Objection 1: Science is in the reason only: hence the comparison fails, as stated above [*Cf. FS, Q[53], A[1]].
Reply to Objection 2: The experience required by prudence results not from memory alone, but also from the practice of commanding aright.
Reply to Objection 3: Prudence consists chiefly, not in the knowledge of universals, but in applying them to action, as stated above (A[3]). Wherefore forgetting the knowledge of universals does not destroy the principal part of prudence, but hinders it somewhat, as stated above.