1265–1273 · Thomas Aquinas, Summa Theologica II-II, q. 115, a. 1, ad 1
Reply to Objection 1: One may praise a person both well and ill, according as one observes or omits the due circumstances. For if while observing other due circumstances one were to wish to please a person by praising him, in order thereby to console him, or that he may strive to make progress in good, this will belong to the aforesaid virtue of friendship. But it would belong to flattery, if one wished to praise a person for things in which he ought not to be praised; since perhaps they are evil, according to Ps. 9:24, "The sinner is praised in the desires of his soul"; or they may be uncertain, according to Ecclus. 27:8, "Praise not a man before he speaketh," and again (Ecclus. 11:2), "Praise not a man for his beauty"; or because there may be fear lest human praise should incite him to vainglory, wherefore it is written, (Ecclus. 11:30), "Praise not any man before death." Again, in like manner it is right to wish to please a man in order to foster charity, so that he may make spiritual progress therein. But it would be sinful to wish to please men for the sake of vainglory or gain, or to please them in something evil, according to Ps. 52:6, "God hath scattered the bones of them that please men," and according to the words of the Apostle (Gal. 1:10), "If I yet pleased men, I should not be the servant of Christ."