263 It is a duty, then, to take care of and to restore what has been entrusted to us. But meanwhile a change comes, either in time or circumstances, so that it is no longer a duty to restore what one has received. As, for instance, when a man demands back his money as an open enemy, to use it against his country, and to offer his wealth to barbarians. Or, if you should have to restore it, while another stood by to extort it from him by force. If you restore money to a raving lunatic when he cannot keep it; if you give up to a madman a sword once put by with you, whereby he may kill himself, is it not an act contrary to duty to pay the debt? Is it not contrary to duty to take knowingly what has been got by a thief, so that he who has lost it is cheated out of it?
264. It is also sometimes contrary to duty to fulfil a promise, or to keep an oath. As was the case with Herod, who swore that whatever was asked he would give to the daughter of Herodias, and so allowed the death of John, that he might not break his word. And what shall I say of Jephthah, who offered up his daughter in sacrifice, she having been the first to meet him as he returned home victorious; whereby he fulfilled the vow which he had made that he would offer to God whatever should meet him first. It would have been better to make no promise at all, than to fulfil it in the death of his daughter.
265. You are not ignorant how important it is to look to this. And so a Levite is chosen to guard the sanctuary, one who shall never fail in counsel, nor forsake the faith, nor fear death, nor do anything extravagant, so that in his whole appearance he may give proof of his earnestness. For he ought to have not only his soul but even his eyes in restraint, so that no chance mishap may bring a blush to his forehead. For “whosoever looks on a woman to desire her has already committed adultery with her in his heart.” Thus adultery is committed not only by actual committal of the foul deed, but even by the desire of the ardent gaze.
266. This seems high and somewhat severe, but in a high office it is not out of place. For the grace of the Levites is such that Moses spoke of them as follows in his blessing: “Give to Levi his men, give Levi his trusted ones, give Levi the lot of his inheritance, and his truth to the holy men whom they tempted in temptation, and reviled at the waters of contradiction. Who said to his father and mother, I know you not, and knew not his brethren, and renounced his children. He guarded Your word and kept Your testimony.”
267. They, then, are His men, His trusty ones, who have no deceit in their hearts, hide no treachery within them, but guard His words and ponder them in their heart, as Mary pondered them; who know not their parents so as to put them before their duty; who hate the violators of chastity, and avenge the injury done to purity; and know the times for the fulfilling of their duty, as also which duty is the greater, which the lesser, and to what occasion each is suited. In all this they follow that alone which is virtuous. And who, where there are two virtuous duties, think that which is the more virtuous must come first. These are in truth rightly blessed.
268. If any one makes known the just works of the Lord, and offers Him incense, then: “Bless, O Lord, his strength; accept the work of his hands,” that he may find the grace of the prophetic blessing with Him Who lives and reigns for ever and ever. Amen.
Source: On the Duties of the Clergy (New Advent)