Article I. On the Obligation of Celebrating by Reason of the Priesthood

359. I say: All priests, by reason of the priesthood, are bound by divine law under grave obligation to celebrate at some time. This is proved from the words of Christ, Luke 22:19: Do this in commemoration of Me. By these words, according to the testimony of the Council of Trent, Christ commanded the Apostles and their successors to offer the Sacrifice. Moreover, all priests receive in their ordination not only the power, but also the charge and office of sacrificing annexed to it. Hence the Apostle, Heb. 5:1: For every high priest taken from among men is ordained for men in the things that appertain to God, that he may offer up gifts and sacrifices. Moreover, in a grave matter everyone is gravely bound to discharge the charge he has undertaken. Therefore.... - Thus St. Thomas, part 3, q. 82, art. 10. - See St. Lig., no. 313.

360. Questions. - QUESTION 1. How often in his life or in a year is a priest bound to celebrate?

Reply. It is not clearly established. More probably, he does not seem bound to celebrate except three or four times in the year, namely, on the more solemn feasts. Indeed, it does not appear improbable that a priest has sufficiently fulfilled his office if, on whatever days they may be, he offers the Sacrifice three or four times in the year. - St. Lig., no. 313.

QUESTION 2. Is one who celebrates only four times in the year exempt from every sin?

Reply. Negatively. For he does not seem excusable from at least some venial sin. Thus commonly, according to the mind of the Council of Trent, sess. 25, ch. 14, De Reform., where it is said: Let the Bishop take care that they (the priests) celebrate Mass at least on Sundays and solemn feasts. Indeed, holy mother Church desires that a priest offer the Sacrifice every day, and devout priests are accustomed to omit it very rarely.

Hence St. Lig., no. 359, deservedly concludes: Wherefore, I would not know how to excuse from light fault that priest who could celebrate daily (one day of the week excepted out of reverence), and who, without any just cause, but solely from sloth, abstained from celebrating; for a priest celebrates not only for himself, but also for the good of the whole Church and of the Christian people, whose minister and intercessor he has been constituted, according to that saying of the Apostle: EVERY HIGH PRIEST taken from among men is ordained for men in the things that appertain to God, that he may offer up gifts and sacrifices for sins.

Deservedly, therefore, the author of the excellent work The Imitation of Christ says, bk. 4, ch. 5: When a priest celebrates, he honors God, gladdens the Angels, edifies the Church, assists the living, affords rest to the dead, and makes himself a partaker of all good things. Thus also St. Bonaventure, On Preparation for Mass, ch. 5: A priest who does not celebrate, so far as lies in him, deprives the Trinity of praise and glory, the Angels of joy, sinners of pardon, the just of assistance and grace, those existing in Purgatory of refreshment, the Church of Christ of a special benefit, and himself of medicine and remedy against daily sins and infirmities.