HKB
(2) Whether it is a mortal sin? _______________________
FIRST ARTICLE [II-II, Q. 112, Art. 1]
Whether Boasting Is Opposed to the Virtue of Truth?
Objection 1: It seems that boasting is not opposed to the virtue of truth. For lying is opposed to truth. But it is possible to boast even without lying, as when a man makes a show of his own excellence. Thus it is written (Esther 1:3, 4) that Assuerus "made a great feast . . . that he might show the riches of the glory" and "of his kingdom, and the greatness and boasting of his power." Therefore boasting is not opposed to the virtue of truth.
Obj. 2: Further, boasting is reckoned by Gregory (Moral. xxiii, 4) to be one of the four species of pride, "when," to wit, "a man boasts of having what he has not." Hence it is written (Jer. 48:29, 30): "We have heard the pride of Moab, he is exceeding proud: his haughtiness, and his arrogancy, and his pride, and the loftiness of his heart. I know, saith the Lord, his boasting, and that the strength thereof is not according to it." Moreover, Gregory says (Moral. xxxi, 7) that boasting arises from vainglory. Now pride and vainglory are opposed to the virtue of humility. Therefore boasting is opposed, not to truth, but to humility.
Obj. 3: Further, boasting seems to be occasioned by riches; wherefore it is written (Wis. 5:8): "What hath pride profited us? or what advantage hath the boasting of riches brought us?" Now excess of riches seems to belong to the sin of covetousness, which is opposed to justice or liberality. Therefore boasting is not opposed to truth.
On the contrary, The Philosopher says (Ethic. ii, 7; iv, 7), that boasting is opposed to truth.
I answer that, Jactantia (boasting) seems properly to denote the uplifting of self by words: since if a man wishes to throw (jactare) a thing far away, he lifts it up high. And to uplift oneself, properly speaking, is to talk of oneself above oneself [*Or 'tall-talking' as we should say in English]. This happens in two ways. For sometimes a man speaks of himself, not above what he is in himself, but above that which he is esteemed by men to be: and this the Apostle declines to do when he says (2 Cor. 12:6): "I forbear lest any man should think of me above that which he seeth in me, or anything he heareth of me." In another way a man uplifts himself in words, by speaking of himself above that which he is in reality. And since we should judge of things as they are in themselves, rather than as others deem them to be, it follows that boasting denotes more properly the uplifting of self above what one is in oneself, than the uplifting of self above what others think of one: although in either case it may be called boasting. Hence boasting properly so called is opposed to truth by way of excess.
Reply Obj. 1: This argument takes boasting as exceeding men's opinion.