Chapter — Wouters, Manual of Moral Theology
Chapter I. On Theological Virtues in General
I. Notion. The principles, as St. Thomas teaches, by which man is ordered to supernatural beatitude are called theological virtues, "both because they have God as object, insofar as by them we are rightly ordered to God; and because they are infused into us by God alone; and because only by divine revelation in Sacred Scripture are virtues of this kind handed down" (St. Thomas, I-II, q. 62, a. 1).
Therefore for a threefold reason these principles are called theological virtues: by reason of object, by reason of cause, and by reason of cognition. The first reason, as being of greatest importance for our scope, will be explained briefly.
In order that a virtue, by reason of its object, may claim for itself as proper the name theological virtue, it must on the one hand have God Himself as its immediate material object. Otherwise moral virtues, which mediately, i.e., by means of an intermediate end, also attain God as the ultimate end, would have to be called by an equal name. From this, however, it does not follow that God must be the adequate material object, but only the primary; for the things which are attained by reason of the primary object are reduced as a secondary object to the same virtue. Thus, for example, one's neighbor must be called the secondary object of the virtue of charity, since he is attained by reason of the primary object, which is God.
On the other hand, God Himself also, or His perfections, must constitute the formal object of theological virtue; for it belongs to the formal object to constitute a virtue in its species. Hence, in order to constitute some virtue in the species of theological virtue, God Himself or His divine attributes must be the formal object of that virtue.
From what has been said it follows that theological virtue is aptly defined: A virtue whose immediate object, both material, at least principal, and formal, is God Himself as author and end of the supernatural order.
II. Number. That the theological virtues are only three in number, namely faith, hope, and charity, the universal Church has always held as certain, and in this sense also interprets the words of the Apostle: "And now there remain faith, hope, charity, these three; but the greater of these is charity."1 For no reason can be assigned why the Apostle enumerates these virtues as three distinct species of one genus, distinct from all other virtues, unless because these three are theological exclusively.2 It is also confirmed by reason. For in order that man may arrive at the supernatural end, he must tend stably toward it by operations of intellect and will proportioned to this end. Now for this, three theological virtues are required: faith, namely, which perfects the intellect for knowing the supernatural end; hope, which perfects the will for firmly desiring the same end as possible of attainment and perfective of the one desiring; and charity, which perfects the will for firmly desiring the aforesaid end as a good in itself, to which man must order himself and whatever else.3
1 1 Cor. 13:13.
2 Cf. Origen, bk. 4, Commentary on the Epistle to the Romans, c. 4, n. 6; St. Augustine, sermon 27, n. 1; Enchiridion, c. 6, n. 1 and c. 9, n. 2, at the end; St. Gregory the Great, bk. 1, Moralia, c. 27, n. 38.
3 Cf. Salmanticenses, commentary on I-II, q. 62, a. 3; Mazzella, nn. 43-44.