Summa Th. III EN Qu.82 a.5

Whether a wicked priest can consecrate the Eucharist?

Objection: 1. It seems that a wicked priest cannot consecrate the Eucharist. For Jerome, commenting on Sophon. iii, 4, says: "The priests who perform the Eucharist, and who distribute our Lord's blood to the people, act wickedly against Christ's law, in deeming that the Eucharist is consecrated by a prayer rather than by a good life; and that only the solemn prayer is requisite, and not the priest's merits: of whom it is said: 'Let not the priest, in whatever defilement he may be, approach to offer oblations to the Lord'" (Lv 21,21, Septuagint). But the sinful priest, being defiled, has neither the life nor the merits befitting this sacrament. Therefore a sinful priest cannot consecrate the Eucharist.
2. Further, Damascene says (De Fide Orth. iv) that "the bread and wine are changed supernaturally into the body and blood of our Lord, by the coming of the Holy Ghost." But Pope Gelasius I says (Ep ad Elphid., cf. Decret. i, q. 1): "How shall the Holy Spirit, when invoked, come for the consecration of the Divine Mystery, if the priest invoking him be proved full of guilty deeds?" Consequently, the Eucharist cannot be consecrated by a wicked priest.
3. Further, this sacrament is consecrated by the priest's blessing. But a sinful priest's blessing is not efficacious for consecrating this sacrament, since it is written (Ml 2,2): "I will curse your blessings." Again, Dionysius says in his Epistle (viii) to the monk Demophilus: "He who is not enlightened has completely fallen away from the priestly order; and I wonder that such a man dare to employ his hands in priestly actions, and in the person of Christ to utter, over the Divine symbols, his unclean infamies, for I will not call them prayers."

On the contrary Augustine (Paschasius) says (De Corp. Dom. xii): "Within the Catholic Church, in the mystery of the Lord's body and blood, nothing greater is done by a good priest, nothing less by an evil priest, because it is not by the merits of the consecrator that the sacrament is accomplished, but by the Creator's word, and by the power of the Holy Spirit."
I answer that As was said above (Articles [1],3), the priest consecrates this sacrament not by his own power, but as the minister of Christ, in Whose person he consecrates this sacrament. But from the fact of being wicked he does not cease to be Christ's minister; because our Lord has good and wicked ministers or servants. Hence (Mt 24,45) our Lord says: "Who, thinkest thou, is a faithful and wise servant?" and afterwards He adds: "But if that evil servant shall say in his heart," etc. And the Apostle (1Co 4,1) says: "Let a man so account of us as of the ministers of Christ"; and afterwards he adds: "I am not conscious to myself of anything; yet am I not hereby justified." He was therefore certain that he was Christ's minister; yet he was not certain that he was a just man. Consequently, a man can be Christ's minister even though he be not one of the just. And this belongs to Christ's excellence, Whom, as the true God, things both good and evil serve, since they are ordained by His providence for His glory. Hence it is evident that priests, even though they be not godly, but sinners, can consecrate the Eucharist.

Reply to Objection: 1. In those words Jerome is condemning the error of priests who believed they could consecrate the Eucharist worthily, from the mere fact of being priests, even though they were sinners; and Jerome condemns this from the fact that persons defiled are forbidden to approach the altar; but this does not prevent the sacrifice, which they offer, from being a true sacrifice, if they do approach.
2. Previous to the words quoted, Pope Gelasius expresses himself as follows: "That most holy rite, which contains the Catholic discipline, claims for itself such reverence that no one may dare to approach it except with clean conscience." From this it is evident that his meaning is that the priest who is a sinner ought not to approach this sacrament. Hence when he resumes, "How shall the Holy Spirit come when summoned," it must be understood that He comes, not through the priest's merits, but through the power of Christ, Whose words the priest utters.
3. As the same action can be evil, inasmuch as it is done with a bad intention of the servant; and good from the good intention of the master; so the blessing of a sinful priest, inasmuch as he acts unworthily is deserving of a curse, and is reputed an infamy and a blasphemy, and not a prayer; whereas, inasmuch as it is pronounced in the person of Christ, it is holy and efficacious. Hence it is said with significance: "I will curse your blessings."

Whether the mass of a sinful priest is of less worth than the mass of a good priest?

Objection: 1. It seems that the mass of a sinful priest is not of less worth than that of a good priest. For Pope Gregory says in the Register: "Alas, into what a great snare they fall who believe that the Divine and hidden mysteries can be sanctified more by some than by others; since it is the one and the same Holy Ghost Who hallows those mysteries in a hidden and invisible manner." But these hidden mysteries are celebrated in the mass. Therefore the mass of a sinful priest is not of less value than the mass of a good priest.
2. Further, as Baptism is conferred by a minister through the power of Christ Who baptizes, so likewise this sacrament is consecrated in the person of Christ. But Baptism is no better when conferred by a better priest, as was said above (Question [64], Article [1], ad 2). Therefore neither is a mass the better, which is celebrated by a better priest.
3. Further, as the merits of priests differ in the point of being good and better, so they likewise differ in the point of being good and bad. Consequently, if the mass of a better priest be itself better, it follows that the mass of a bad priest must be bad. Now this is unreasonable, because the malice of the ministers cannot affect Christ's mysteries, as Augustine says in his work on Baptism (Contra Donat. xii). Therefore neither is the mass of a better priest the better.

On the contrary It is stated in Decretal i, q. 1: "The worthier the priest, the sooner is he heard in the needs for which he prays."
I answer that There are two things to be considered in the mass. namely, the sacrament itself, which is the chief thing; and the prayers which are offered up in the mass for the quick and the dead. So far as the mass itself is concerned, the mass of a wicked priest is not of less value than that of a good priest, because the same sacrifice is offered by both.Again, the prayer put up in the mass can be considered in two respects: first of all, in so far as it has its efficacy from the devotion of the priest interceding, and in this respect there is no doubt but that the mass of the better priest is the more fruitful. In another respect, inasmuch as the prayer is said by the priest in the mass in the place of the entire Church, of which the priest is the minister; and this ministry remains even in sinful men, as was said above (Article [5]) in regard to Christ's ministry. Hence, in this respect the prayer even of the sinful priest is fruitful, not only that which he utters in the mass, but likewise all those he recites in the ecclesiastical offices, wherein he takes the place of the Church. on the other hand, his private prayers are not fruitful, according to Pr 28,9: "He that turneth away his ears from hearing the law, his prayer shall be an abomination."

Reply to Objection: 1. Gregory is speaking there of the holiness of the Divine sacrament.
2. In the sacrament of Baptism solemn prayers are not made for all the faithful, as in the mass; therefore there is no parallel in this respect. There is, however, a resemblance as to the effect of the sacrament.
3. By reason of the power of the Holy Ghost, Who communicates to each one the blessings of Christ's members on account of their being united in charity, the private blessing in the mass of a good priest is fruitful to others. But the private evil of one man cannot hurt another, except the latter, in some way, consent, as Augustine says (Contra Parmen. ii).

Whether heretics, schismatics, and excommunicated persons can consecrate?

Objection: 1. It seems that heretics, schismatics, and excommunicated persons are not able to consecrate the Eucharist. For Augustine says (Liber sentent. Prosperi xv) that "there is no such thing as a true sacrifice outside the Catholic Church": and Pope Leo I says (Ep. lxxx; cf. Decretal i, q. 1): Elsewhere "(i.e. than in the Church which is Christ's body) there is neither valid priesthood nor true sacrifice." But heretics, schismatics, and excommunicated persons are severed from the Church. Therefore they are unable to offer a true sacrifice.
2. Further (Decretal, caus. i, q. 1), Innocent I is quoted as saying: "Because we receive the laity of the Arians and other pestilential persons, if they seem to repent, it does not follow that their clergy have the dignity of the priesthood or of any other ministerial office, for we allow them to confer nothing save Baptism." But none can consecrate the Eucharist, unless he have the dignity of the priesthood. Therefore heretics and the like cannot consecrate the Eucharist.
3. Further, it does not seem feasible for one outside the Church to act on behalf of the Church. But when the priest consecrates the Eucharist, he does so in the person of the entire Church, as is evident from the fact of his putting up all prayers in the person of the Church. Therefore, it seems that those who are outside the Church, such as those who are heretics, schismatics, and excommunicate, are not able to consecrate the Eucharist.

On the contrary Augustine says (Contra Parmen. ii): "Just as Baptism remains in them," i.e. in heretics, schismatics, and those who are excommunicate, "so do their orders remain intact." Now, by the power of his ordination, a priest can consecrate the Eucharist. Therefore, it seems that heretics, schismatics, and those who are excommunicate, can consecrate the Eucharist, since their orders remain entire.
I answer that Some have contended that heretics, schismatics, and the excommunicate, who are outside the pale of the Church, cannot perform this sacrament. But herein they are deceived, because, as Augustine says (Contra Parmen. ii), "it is one thing to lack something utterly, and another to have it improperly"; and in like fashion, "it is one thing not to bestow, and quite another to bestow, but not rightly." Accordingly, such as, being within the Church, received the power of consecrating the Eucharist through being ordained to the priesthood, have such power rightly indeed; but they use it improperly if afterwards they be separated from the Church by heresy, schism, or excommunication. But such as are ordained while separated from the Church, have neither the power rightly, nor do they use it rightly. But that in both cases they have the power, is clear from what Augustine says (Contra Parmen. ii), that when they return to the unity of the Church, they are not re-ordained, but are received in their orders. And since the consecration of the Eucharist is an act which follows the power of order, such persons as are separated from the Church by heresy, schism, or excommunication, can indeed consecrate the Eucharist, which on being consecrated by them contains Christ's true body and blood; but they act wrongly, and sin by doing so; and in consequence they do not receive the fruit of the sacrifice, which is a spiritual sacrifice.

Reply to Objection: 1. Such and similar authorities are to be understood in this sense, that the sacrifice is offered wrongly outside the Church. Hence outside the Church there can be no spiritual sacrifice that is a true sacrifice with the truth of its fruit, although it be a true sacrifice with the truth of the sacrament; thus it was stated above (Question [80], Article [3]), that the sinner receives Christ's body sacramentally, but not spiritually.
2. Baptism alone is allowed to be conferred by heretics, and schismatics, because they can lawfully baptize in case of necessity; but in no case can they lawfully consecrate the Eucharist, or confer the other sacraments.
3. The priest, in reciting the prayers of the mass, speaks instead of the Church, in whose unity he remains; but in consecrating the sacrament he speaks as in the person of Christ, Whose place he holds by the power of his orders. Consequently, if a priest severed from the unity of the Church celebrates mass, not having lost the power of order, he consecrates Christ's true body and blood; but because he is severed from the unity of the Church, his prayers have no efficacy.

Whether a degraded priest can consecrate this sacrament?

Objection: 1. It seems that a degraded priest cannot consecrate this sacrament. For no one can perform this sacrament except he have the power of consecrating. But the priest "who has been degraded has no power of consecrating, although he has the power of baptizing" (App. Gratiani). Therefore it seems that a degraded priest cannot consecrate the Eucharist.
2. Further, he who gives can take away. But the bishop in ordaining gives to the priest the power of consecrating. Therefore he can take it away by degrading him.
3. Further, the priest, by degradation, loses either the power of consecrating, or the use of such power. But he does not lose merely the use, for thus the degraded one would lose no more than one excommunicated, who also lacks the use. Therefore it seems that he loses the power to consecrate, and in consequence that he cannot perform this sacrament.

On the contrary Augustine (Contra Parmen. ii) proves that "apostates" from the faith "are not deprived of their Baptism," from the fact that "it is not restored to them when they return repentant; and therefore it is deemed that it cannot be lost." But in like fashion, if the degraded man be restored, he has not to be ordained over again. Consequently, he has not lost the power of consecrating, and so the degraded priest can perform this sacrament.
I answer that The power of consecrating the Eucharist belongs to the character of the priestly order. But every character is indelible, because it is given with a kind of consecration, as was said above (Question [63], Article [5]), just as the consecrations of all other things are perpetual, and cannot be lost or repeated. Hence it is clear that the power of consecrating is not lost by degradation. For, again, Augustine says (Contra Parmen. ii): "Both are sacraments," namely Baptism and order, "and both are given to a man with a kind of consecration; the former, when he is baptized; the latter when he is ordained; and therefore it is not lawful for Catholics to repeat either of them." And thus it is evident that the degraded priest can perform this sacrament.

Reply to Objection: 1. That Canon is speaking, not as by way of assertion, but by way of inquiry, as can be gleaned from the context.
2. The bishop gives the priestly power of order, not as though coming from himself, but instrumentally, as God's minister, and its effect cannot be taken away by man, according to Mt 19,6: "What God hath joined together, let no man put asunder." And therefore the bishop cannot take this power away, just as neither can he who baptizes take away the baptismal character.
3. Excommunication is medicinal. And therefore the ministry of the priestly power is not taken away from the excommunicate, as it were, perpetually, but only for a time, that they may mend; but the exercise is withdrawn from the degraded, as though condemned perpetually.

Whether it is permissible to receive communion from heretical, excommunicate, or sinful priests, and to hear mass said by them?

Objection: 1. It seems that one may lawfully receive Communion from heretical, excommunicate, or even sinful priests, and to hear mass said by them. Because, as Augustine says (Contra Petilian. iii), "we should not avoid God's sacraments, whether they be given by a good man or by a wicked one." But priests, even if they be sinful, or heretics, or excommunicate, perform a valid sacrament. Therefore it seems that one ought not to refrain from receiving Communion at their hands, or from hearing their mass.
2. Further, Christ's true body is figurative of His mystical body, as was said above (Question [67], Article [2]). But Christ's true body is consecrated by the priests mentioned above. Therefore it seems that whoever belongs to His mystical body can communicate in their sacrifices.
3. Further, there are many sins graver than fornication. But it is not forbidden to hear the masses of priests who sin otherwise. Therefore, it ought not to be forbidden to hear the masses of priests guilty of this sin.

On the contrary The Canon says (Dist. 32): "Let no one hear the mass of a priest whom he knows without doubt to have a concubine." Moreover, Gregory says (Dial. iii) that "the faithless father sent an Arian bishop to his son, for him to receive sacrilegiously the consecrated Communion at his hands. But, when the Arian bishop arrived, God's devoted servant rebuked him, as was right for him to do."
I answer that As was said above (Articles [5],7), heretical, schismatical, excommunicate, or even sinful priests, although they have the power to consecrate the Eucharist, yet they do not make a proper use of it; on the contrary, they sin by using it. But whoever communicates with another who is in sin, becomes a sharer in his sin. Hence we read in John's Second Canonical Epistle (11) that "He that saith unto him, God speed you, communicateth with his wicked works." Consequently, it is not lawful to receive Communion from them, or to assist at their mass.Still there is a difference among the above, because heretics, schismatics, and excommunicates, have been forbidden, by the Church's sentence, to perform the Eucharistic rite. And therefore whoever hears their mass or receives the sacraments from them, commits sin. But not all who are sinners are debarred by the Church's sentence from using this power: and so, although suspended by the Divine sentence, yet they are not suspended in regard to others by any ecclesiastical sentence: consequently, until the Church's sentence is pronounced, it is lawful to receive Communion at their hands, and to hear their mass. Hence on 1Co 5,11, "with such a one not so much as to eat," Augustine's gloss runs thus: "In saying this he was unwilling for a man to be judged by his fellow man on arbitrary suspicion, or even by usurped extraordinary judgment, but rather by God's law, according to the Church's ordering, whether he confess of his own accord, or whether he be accused and convicted."

Reply to Objection: 1. By refusing to hear the masses of such priests, or to receive Communion from them, we are not shunning God's sacraments; on the contrary, by so doing we are giving them honor (hence a host consecrated by such priests is to be adored, and if it be reserved, it can be consumed by a lawful priest): but what we shun is the sin of the unworthy ministers.
2. The unity of the mystical body is the fruit of the true body received. But those who receive or minister unworthily, are deprived of the fruit, as was said above (Article [7]; Question [80], Article [4]). And therefore, those who belong to the unity of the Faith are not to receive the sacrament from their dispensing.
3. Although fornication is not graver than other sins, yet men are more prone to it, owing to fleshly concupiscence. Consequently, this sin is specially inhibited to priests by the Church, lest anyone hear the mass of one living in concubinage. However, this is to be understood of one who is notorious, either from being convicted and sentenced, or from having acknowledged his guilt in legal form, or from it being impossible to conceal his guilt by any subterfuge.

Whether it is lawful for a priest to refrain entirely from consecrating the Eucharist?

Objection: 1. It seems to be lawful for a priest to refrain entirely from consecrating the Eucharist. Because, as it is the priest's office to consecrate the Eucharist, so it is likewise to baptize and administer the other sacraments. But the priest is not bound to act as a minister of the other sacraments, unless he has undertaken the care of souls. Therefore, it seems that likewise he is not bound to consecrate the Eucharist except he be charged with the care of souls.
2. Further, no one is bound to do what is unlawful for him to do; otherwise he would be in two minds. But it is not lawful for the priest who is in a state of sin, or excommunicate, to consecrate the Eucharist, as was said above (Article [7]). Therefore it seems that such men are not bound to celebrate, and so neither are the others; otherwise they would be gainers by their fault.
3. Further, the priestly dignity is not lost by subsequent weakness: because Pope Gelasius I says (cf. Decretal, Dist. 55): "As the canonical precepts do not permit them who are feeble in body to approach the priesthood, so if anyone be disabled when once in that state, he cannot lose that he received at the time he was well." But it sometimes happens that those who are already ordained as priests incur defects whereby they are hindered from celebrating, such as leprosy or epilepsy, or the like. Consequently, it does not appear that priests are bound to celebrate.

On the contrary Ambrose says in one of his Orations (xxxiii): "It is a grave matter if we do not approach Thy altar with clean heart and pure hands; but it is graver still if while shunning sins we also fail to offer our sacrifice."
I answer that Some have said that a priest may lawfully refrain altogether from consecrating, except he be bound to do so, and to give the sacraments to the people, by reason of his being entrusted with the care of souls.But this is said quite unreasonably, because everyone is bound to use the grace entrusted to him, when opportunity serves, according to 2Co 6,1: "We exhort you that you receive not the grace of God in vain." But the opportunity of offering sacrifice is considered not merely in relation to the faithful of Christ to whom the sacraments must be administered, but chiefly with regard to God to Whom the sacrifice of this sacrament is offered by consecrating. Hence, it is not lawful for the priest, even though he has not the care of souls, to refrain altogether from celebrating; and he seems to be bound to celebrate at least on the chief festivals, and especially on those days on which the faithful usually communicate. And hence it is that (2M 2M 4,14) it is said against some priests that they "were not now occupied about the offices of the altar . . . despising the temple and neglecting the sacrifices."

Reply to Objection: 1. The other sacraments are accomplished in being used by the faithful, and therefore he alone is bound to administer them who has undertaken the care of souls. But this sacrament is performed in the consecration of the Eucharist, whereby a sacrifice is offered to God, to which the priest is bound from the order he has received.
2. The sinful priest, if deprived by the Church's sentence from exercising his order, simply or for a time, is rendered incapable of offering sacrifice; consequently, the obligation lapses. But if not deprived of the power of celebrating, the obligation is not removed; nor is he in two minds, because he can repent of his sin and then celebrate.
3. Weakness or sickness contracted by a priest after his ordination does not deprive him of his orders; but hinders him from exercising them, as to the consecration of the Eucharist: sometimes by making it impossible to exercise them, as, for example, if he lose his sight, or his fingers, or the use of speech; and sometimes on account of danger, as in the case of one suffering from epilepsy, or indeed any disease of the mind; and sometimes, on account of loathsomeness, as is evident in the case of a leper, who ought not to celebrate in public: he can, however, say mass privately, unless the leprosy has gone so far that it has rendered him incapable owing to the wasting away of his limbs.


We have now to consider the Rite of this sacrament, under which head there are six points of inquiry:

(1) Whether Christ is sacrificed in the celebration of this mystery?

(2) Of the time of celebrating;

(3) Of the place and other matters relating to the equipment for this celebration;

(4) Of the words uttered in celebrating this mystery;

(5) Of the actions performed in celebrating this mystery.

(6) Of the defects which occur in the celebration of this sacrament.

Whether Christ is sacrificed in this sacrament?

Objection: 1. It seems that Christ is not sacrificed in the celebration of this sacrament. For it is written (He 10,14) that "Christ by one oblation hath perfected for ever them that are sanctified." But that oblation was His oblation. Therefore Christ is not sacrificed in the celebration of this sacrament.
2. Further, Christ's sacrifice was made upon the cross, whereon "He delivered Himself for us, an oblation and a sacrifice to God for an odor of sweetness," as is said in Ep 5,2. But Christ is not crucified in the celebration of this mystery. Therefore, neither is He sacrificed.
3. Further, as Augustine says (De Trin. iv), in Christ's sacrifice the priest and the victim are one and the same. But in the celebration of this sacrament the priest and the victim are not the same. Therefore, the celebration of this sacrament is not a sacrifice of Christ.

On the contrary Augustine says in the Liber Sentent. Prosp. (cf. Ep. xcviii): "Christ was sacrificed once in Himself, and yet He is sacrificed daily in the Sacrament."
I answer that The celebration of this sacrament is called a sacrifice for two reasons. First, because, as Augustine says (Ad Simplician. ii), "the images of things are called by the names of the things whereof they are the images; as when we look upon a picture or a fresco, we say, 'This is Cicero and that is Sallust.'" But, as was said above (Question [79], Article [1]), the celebration of this sacrament is an image representing Christ's Passion, which is His true sacrifice. Accordingly the celebration of this sacrament is called Christ's sacrifice. Hence it is that Ambrose, in commenting on He 10,1, says: "In Christ was offered up a sacrifice capable of giving eternal salvation; what then do we do? Do we not offer it up every day in memory of His death?" Secondly it is called a sacrifice, in respect of the effect of His Passion: because, to wit, by this sacrament, we are made partakers of the fruit of our Lord's Passion. Hence in one of the Sunday Secrets (Ninth Sunday after Pentecost) we say: "Whenever the commemoration of this sacrifice is celebrated, the work of our redemption is enacted." Consequently, according to the first reason, it is true to say that Christ was sacrificed, even in the figures of the Old Testament: hence it is stated in the Apocalypse (13:8): "Whose names are not written in the Book of Life of the Lamb, which was slain from the beginning of the world." But according to the second reason, it is proper to this sacrament for Christ to be sacrificed in its celebration.

Reply to Objection: 1. As Ambrose says (commenting on He 10,1), "there is but one victim," namely that which Christ offered, and which we offer, "and not many victims, because Christ was offered but once: and this latter sacrifice is the pattern of the former. For, just as what is offered everywhere is one body, and not many bodies, so also is it but one sacrifice."
2. As the celebration of this sacrament is an image representing Christ's Passion, so the altar is representative of the cross itself, upon which Christ was sacrificed in His proper species.
3. For the same reason (cf. Reply Objection [2]) the priest also bears Christ's image, in Whose person and by Whose power he pronounces the words of consecration, as is evident from what was said above (Question [82], Articles [1],3). And so, in a measure, the priest and victim are one and the same.

Whether the time for celebrating this mystery has been properly determined?

Objection: 1. It seems that the time for celebrating this mystery has not been properly determined. For as was observed above (Article [1]), this sacrament is representative of our Lord's Passion. But the commemoration of our Lord's Passion takes place in the Church once in the year: because Augustine says (Enarr. ii in Ps 21): "Is not Christ slain as often as the Pasch is celebrated? Nevertheless, the anniversary remembrance represents what took place in by-gone days; and so it does not cause us to be stirred as if we saw our Lord hanging upon the cross." Therefore this sacrament ought to be celebrated but once a year.
2. Further, Christ's Passion is commemorated in the Church on the Friday before Easter, and not on Christmas Day. Consequently, since this sacrament is commemorative of our Lord's Passion, it seems unsuitable for this sacrament to be celebrated thrice on Christmas Day, and to be entirely omitted on Good Friday.
3. Further, in the celebration of this sacrament the Church ought to imitate Christ's institution. But it was in the evening that Christ consecrated this sacrament. Therefore it seems that this sacrament ought to be celebrated at that time of day.
4. Further, as is set down in the Decretals (De Consecr., dist. i), Pope Leo I wrote to Dioscorus, Bishop of Alexandria, that "it is permissible to celebrate mass in the first part of the day." But the day begins at midnight, as was said above (Question [80], Article [8], ad 5). Therefore it seems that after midnight it is lawful to celebrate.
5. Further, in one of the Sunday Secrets (Ninth Sunday after Pentecost) we say: "Grant us, Lord, we beseech Thee, to frequent these mysteries." But there will be greater frequency if the priest celebrates several times a day. Therefore it seems that the priest ought not to be hindered from celebrating several times daily.

On the contrary On the contrary is the custom which the Church observes according to the statutes of the Canons.
I answer that As stated above (Article [1]), in the celebration of this mystery, we must take into consideration the representation of our Lord's Passion, and the participation of its fruits; and the time suitable for the celebration of this mystery ought to be determined by each of these considerations. Now since, owing to our daily defects, we stand in daily need of the fruits of our Lord's Passion, this sacrament is offered regularly every day in the Church. Hence our Lord teaches us to pray (Lc 11,3): "Give us this day our daily bread": in explanation of which words Augustine says (De Verb. Dom. xxviii): "If it be a daily bread, why do you take it once a year, as the Greeks have the custom in the east? Receive it daily that it may benefit you every day."But since our Lord's Passion was celebrated from the third to the ninth hour, therefore this sacrament is solemnly celebrated by the Church in that part of the day.

Reply to Objection: 1. Christ's Passion is recalled in this sacrament, inasmuch as its effect flows out to the faithful; but at Passion-tide Christ's Passion is recalled inasmuch as it was wrought in Him Who is our Head. This took place but once; whereas the faithful receive daily the fruits of His Passion: consequently, the former is commemorated but once in the year, whereas the latter takes place every day, both that we may partake of its fruit and in order that we may have a perpetual memorial.
2. The figure ceases on the advent of the reality. But this sacrament is a figure and a representation of our Lord's Passion, as stated above. And therefore on the day on which our Lord's Passion is recalled as it was really accomplished, this sacrament is not consecrated. Nevertheless, lest the Church be deprived on that day of the fruit of the Passion offered to us by this sacrament, the body of Christ consecrated the day before is reserved to be consumed on that day; but the blood is not reserved, on account of danger, and because the blood is more specially the image of our Lord's Passion, as stated above (Question [78], Article [3], ad 2). Nor is it true, as some affirm, that the wine is changed into blood when the particle of Christ's body is dropped into it. Because this cannot be done otherwise than by consecration under the due form of words.On Christmas Day, however, several masses are said on account of Christ's threefold nativity. Of these the first is His eternal birth, which is hidden in our regard. and therefore one mass is sung in the night, in the "Introit" of which we say: "The Lord said unto Me: Thou art My Son, this day have I begotten Thee." The second is His nativity in time, and the spiritual birth, whereby Christ rises "as the day-star in our [Vulg.: 'your'] hearts" (2P 1,19), and on this account the mass is sung at dawn, and in the "Introit" we say: "The light will shine on us today." The third is Christ's temporal and bodily birth, according as He went forth from the virginal womb, becoming visible to us through being clothed with flesh: and on that account the third mass is sung in broad daylight, in the "Introit" of which we say: "A child is born to us." Nevertheless, on the other hand, it can be said that His eternal generation, of itself, is in the full light, and on this account in the gospel of the third mass mention is made of His eternal birth. But regarding His birth in the body, He was literally born during the night, as a sign that He came to the darknesses of our infirmity; hence also in the midnight mass we say the gospel of Christ's nativity in the flesh. Likewise on other days upon which many of God's benefits have to be recalled or besought, several masses are celebrated on one day, as for instance, one for the feast, and another for a fast or for the dead.
3. As already observed (Question [73], Article [5]), Christ wished to give this sacrament last of all, in order that it might make a deeper impression on the hearts of the disciples; and therefore it was after supper, at the close of day, that He consecrated this sacrament and gave it to His disciples. But we celebrate at the hour when our Lord suffered, i.e. either, as on feast-days, at the hour of Terce, when He was crucified by the tongues of the Jews (Mc 15,25), and when the Holy Ghost descended upon the disciples (Ac 2,15); or, as when no feast is kept, at the hour of Sext, when He was crucified at the hands of the soldiers (Jn 19,14), or, as on fasting days, at None, when crying out with a loud voice He gave up the ghost (Mt 27,46 Mt 27,50). Nevertheless the mass can be postponed, especially when Holy orders have to be conferred, and still more on Holy Saturday; both on account of the length of the office, and also because orders belong to the Sunday, as is set forth in the Decretals (dist. 75).Masses, however, can be celebrated "in the first part of the day," owing to any necessity; as is stated De Consecr., dist. 1.
4. As a rule mass ought to be said in the day and not in the night, because Christ is present in this sacrament, Who says (Jn 9,4-5): "I must work the works of Him that sent Me, whilst it is day: because the night cometh when no man can work; as long as I am in the world, I am the light of the world." Yet this should be done in such a manner that the beginning of the day is not to be taken from midnight; nor from sunrise, that is, when the substance of the sun appears above the earth; but when the dawn begins to show: because then the sun is said to be risen when the brightness of his beams appears. Accordingly it is written (Mc 16,1) that "the women came to the tomb, the sun being now risen"; though, as John relates (Jn 20,1), "while it was yet dark they came to the tomb." It is in this way that Augustine explains this difference (De Consens. Evang. iii). Exception is made on the night of Christmas eve, when mass is celebrated, because our Lord was born in the night (De Consecr., dist. 1). And in like manner it is celebrated on Holy Saturday towards the beginning of the night, since our Lord rose in the night, that is, "when it was yet dark, before the sun's rising was manifest."
5. As is set down in the decree (De Consecr., dist. 1), in virtue of a decree of Pope Alexander II, "it is enough for a priest to celebrate one mass each day, because Christ suffered once and redeemed the whole world; and very happy is he who can worthily celebrate one mass. But there are some who say one mass for the dead, and another of the day, if need be. But I do not deem that those escape condemnation who presume to celebrate several masses daily, either for the sake of money, or to gain flattery from the laity." And Pope Innocent III says (Extra, De Celebr. Miss., chap. Consuluisti) that "except on the day of our Lord's birth, unless necessity urges, it suffices for a priest to celebrate only one mass each day."

Summa Th. III EN Qu.82 a.5