On the contrary, Macrobius [*In Somn. Scip. i, 8] reckons it to be a part of temperance.
I answer that, The word "chastity" is employed in two ways. First, properly; and thus it is a special virtue having a special matter, namely the concupiscences relating to venereal pleasures. Secondly, the word "chastity" is employed metaphorically: for just as a mingling of bodies conduces to venereal pleasure which is the proper matter of chastity and of lust its contrary vice, so too the spiritual union of the mind with certain things conduces to a pleasure which is the matter of a spiritual chastity metaphorically speaking, as well as of a spiritual fornication likewise metaphorically so called. For if the human mind delight in the spiritual union with that to which it behooves it to be united, namely God, and refrains from delighting in union with other things against the requirements of the order established by God, this may be called a spiritual chastity, according to 2 Cor. 11:2, "I have espoused you to one husband, that I may present you as a chaste virgin to Christ." If, on the other hand, the mind be united to any other things whatsoever, against the prescription of the Divine order, it will be called spiritual fornication, according to Jer. 3:1, "But thou hast prostituted thyself to many lovers." Taking chastity in this sense, it is a general virtue, because every virtue withdraws the human mind from delighting in a union with unlawful things. Nevertheless, the essence of this chastity consists principally in charity and the other theological virtues, whereby the human mind is united to God.
Reply Obj. 1: This argument takes chastity in the metaphorical sense.
Reply Obj. 2: As stated above (A. 1; Q. 142, A. 2), the concupiscence of that which gives pleasure is especially likened to a child, because the desire of pleasure is connatural to us, especially of pleasures of touch which are directed to the maintenance of nature. Hence it is that if the concupiscence of such pleasures be fostered by consenting to it, it will wax very strong, as in the case of a child left to his own will. Wherefore the concupiscence of these pleasures stands in very great need of being chastised: and consequently chastity is applied antonomastically to such like concupiscences, even as fortitude is about those matters wherein we stand in the greatest need of strength of mind.
Reply Obj. 3: This argument considers spiritual fornication metaphorically so called, which is opposed to spiritual chastity, as stated. _______________________
THIRD ARTICLE [II-II, Q. 151, Art. 3]
Whether Chastity Is a Distinct Virtue from Abstinence?
Objection 1: It would seem that chastity is not a distinct virtue from abstinence. Because where the matter is generically the same, one virtue suffices. Now it would seem that things pertaining to the same sense are of one genus. Therefore, since pleasures of the palate which are the matter of abstinence, and venereal pleasures which are the matter of chastity, pertain to the touch, it seems that chastity is not a distinct virtue from abstinence.
Obj. 2: Further, the Philosopher (Ethic. iii, 12) likens all vices of intemperance to childish sins, which need chastising. Now "chastity" takes its name from "chastisement" of the contrary vices. Since then certain vices are bridled by abstinence, it seems that abstinence is chastity.
Obj. 3: Further, the pleasures of the other senses are the concern of temperance in so far as they refer to pleasures of touch; which are the matter of temperance. Now pleasures of the palate, which are the matter of abstinence, are directed to venereal pleasures, which are the matter of chastity: wherefore Jerome says [*Ep. cxlvii ad Amand. Cf. Gratian, Dist. xliv.], commenting on Titus 1:7, "Not given to wine, no striker," etc.: "The belly and the organs of generation are neighbors, that the neighborhood of the organs may indicate their complicity in vice." Therefore abstinence and chastity are not distinct virtues.