Reply Obj. 1: Two points must be considered in the mitigation of punishment. One is that punishment should be mitigated in accordance with the lawgiver's intention, although not according to the letter of the law; and in this respect it pertains to equity. The other point is a certain moderation of a man's inward disposition, so that he does not exercise his power of inflicting punishment. This belongs properly to clemency, wherefore Seneca says (De Clementia ii, 3) that "it is temperance of the soul in exercising the power of taking revenge." This moderation of soul comes from a certain sweetness of disposition, whereby a man recoils from anything that may be painful to another. Wherefore Seneca says (De Clementia ii, 3) that "clemency is a certain smoothness of the soul"; for, on the other hand, there would seem to be a certain roughness of soul in one who fears not to pain others.
Reply Obj. 2: The annexation of secondary to principal virtues depends on the mode of virtue, which is, so to speak, a kind of form of the virtue, rather than on the matter. Now meekness and clemency agree with temperance in mode, as stated above, though they agree not in matter.
Reply Obj. 3: Unsoundness is corruption of soundness. Now just as soundness of body is corrupted by the body lapsing from the condition due to the human species, so unsoundness of mind is due to the mind lapsing from the disposition due to the human species. This occurs both in respect of the reason, as when a man loses the use of reason, and in respect of the appetitive power, as when a man loses that humane feeling whereby "every man is naturally friendly towards all other men" (Ethic. viii, 1). The unsoundness of mind that excludes the use of reason is opposed to prudence. But that a man who takes pleasure in the punishment of others is said to be of unsound mind, is because he seems on this account to be devoid of the humane feeling which gives rise to clemency. _______________________
FOURTH ARTICLE [II-II, Q. 157, Art. 4]
Whether Clemency and Meekness Are the Greatest Virtues?
Objection 1: It would seem that clemency and meekness are the greatest virtues. For virtue is deserving of praise chiefly because it directs man to happiness that consists in the knowledge of God. Now meekness above all directs man to the knowledge of God: for it is written (James 1:21): "With meekness receive the ingrafted word," and (Ecclus. 5:13): "Be meek to hear the word" of God. Again, Dionysius says (Ep. viii ad Demophil.) that "Moses was deemed worthy of the Divine apparition on account of his great meekness." Therefore meekness is the greatest of virtues.
Obj. 2: Further, seemingly a virtue is all the greater according as it is more acceptable to God and men. Now meekness would appear to be most acceptable to God. For it is written (Ecclus. 1:34, 35): "That which is agreeable" to God is "faith and meekness"; wherefore Christ expressly invites us to be meek like unto Himself (Matt. 11:29), where He says: "Learn of Me, because I am meek and humble of heart"; and Hilary declares [*Comment. in Matth. iv, 3] that "Christ dwells in us by our meekness of soul." Again, it is most acceptable to men; wherefore it is written (Ecclus. 3:19): "My son, do thy works in meekness, and thou shalt be beloved above the glory of men": for which reason it is also declared (Prov. 20:28) that the King's "throne is strengthened by clemency." Therefore meekness and clemency are the greatest of virtues.
Obj. 3: Further, Augustine says (De Serm. Dom. in Monte i, 2) that "the meek are they who yield to reproaches, and resist not evil, but overcome evil by good." Now this seems to pertain to mercy or piety which would seem to be the greatest of virtues: because a gloss of Ambrose [*Hilary the deacon] on 1 Tim. 4:8, "Piety [Douay: 'Godliness'] is profitable to all things," observes that "piety is the sum total of the Christian religion." Therefore meekness and clemency are the greatest virtues.
On the contrary, They are not reckoned as principal virtues, but are annexed to another, as to a principal, virtue.
I answer that, Nothing prevents certain virtues from being greatest, not indeed simply, nor in every respect, but in a particular genus. It is impossible for clemency or meekness to be absolutely the greatest virtues, since they owe their praise to the fact that they withdraw a man from evil, by mitigating anger or punishment. Now it is more perfect to obtain good than to lack evil. Wherefore those virtues like faith, hope, charity, and likewise prudence and justice, which direct one to good simply, are absolutely greater virtues than clemency and meekness.