Objection 1. It seems that the words spoken in this sacrament are not properly framed. For, as Ambrose says (De Sacram. iv), this sacrament is consecrated with Christ's own words. Therefore no other words besides Christ's should be spoken in this sacrament.
Objection 2. Further, Christ's words and deeds are made known to us through the Gospel. But in consecrating this sacrament words are used which are not set down in the Gospels: for we do not read in the Gospel, of Christ lifting up His eyes to heaven while consecrating this sacrament: and similarly it is said in the Gospel: "Take ye and eat" [comedite] without the addition of the word "all," whereas in celebrating this sacrament we say: "Lifting up His eyes to heaven," and again, "Take ye and eat [manducate] of this." Therefore such words as these are out of place when spoken in the celebration of this sacrament.
Objection 3. Further, all the other sacraments are ordained for the salvation of all the faithful. But in the celebration of the other sacraments there is no common prayer put up for the salvation of all the faithful and of the departed. Consequently it is unbecoming in this sacrament.
Objection 4. Further, Baptism especially is called the sacrament of faith. Consequently, the truths which belong to instruction in the faith ought rather to be given regarding Baptism than regarding this sacrament, such as the doctrine of the apostles and of the Gospels.
Objection 5. Further, devotion on the part of the faithful is required in every sacrament. Consequently, the devotion of the faithful ought not to be stirred up in this sacrament more than in the others by Divine praises and by admonitions, such as, "Lift up your hearts."
Objection 6. Further, the minister of this sacrament is the priest, as stated above (Question 82, Article 1). Consequently, all the words spoken in this sacrament ought to be uttered by the priest, and not some by the ministers, and some by the choir.
Objection 7. Further, the Divine power works this sacrament unfailingly. Therefore it is to no purpose that the priest asks for the perfecting of this sacrament, saying: "Which oblation do thou, O God, in all," etc.
Objection 8. Further, the sacrifice of the New Law is much more excellent than the sacrifice of the fathers of old. Therefore, it is unfitting for the priest to pray that this sacrifice may be as acceptable as the sacrifice of Abel, Abraham, and Melchisedech.
Objection 9. Further, just as Christ's body does not begin to be in this sacrament by change of place, as stated above (Question 75, Article 2), so likewise neither does it cease to be there. Consequently, it is improper for the priest to ask: "Bid these things be borne by the hands of thy holy angel unto Thine altar on high."
On the contrary, We find it stated in De Consecr., dist. 1, that "James, the brother of the Lord according to the flesh, and Basil, bishop of Caesarea, edited the rite of celebrating the mass": and from their authority it is manifest that whatever words are employed in this matter, are chosen becomingly.
I answer that, Since the whole mystery of our salvation is comprised in this sacrament, therefore is it performed with greater solemnity than the other sacraments. And since it is written (Ecclesiastes 4:17): "Keep thy foot when thou goest into the house of God"; and (Sirach 18:23): "Before prayer prepare thy soul," therefore the celebration of this mystery is preceded by a certain preparation in order that we may perform worthily that which follows after. The first part of this preparation is Divine praise, and consists in the "Introit": according to Psalm 49:23: "The sacrifice of praise shall glorify me; and there is the way by which I will show him the salvation of God": and this is taken for the most part from the Psalms, or, at least, is sung with a Psalm, because, as Dionysius says (Eccl. Hier. iii): "The Psalms comprise by way of praise whatever is contained in Sacred Scripture."
The second part contains a reference to our present misery, by reason of which we pray for mercy, saying: "Lord, have mercy on us," thrice for the Person of the Father, and "Christ, have mercy on us," thrice for the Person of the Son, and "Lord, have mercy on us," thrice for the Person of the Holy Ghost; against the threefold misery of ignorance, sin, and punishment; or else to express the "circuminsession" of all the Divine Persons.
The third part commemorates the heavenly glory, to the possession of which, after this life of misery, we are tending, in the words, "Glory be to God on high," which are sung on festival days, on which the heavenly glory is commemorated, but are omitted in those sorrowful offices which commemorate our unhappy state.
The fourth part contains the prayer which the priest makes for the people, that they may be made worthy of such great mysteries.
There precedes, in the second place, the instruction of the faithful, because this sacrament is "a mystery of faith," as stated above (78, 3, ad 5). Now this instruction is given "dispositively," when the Lectors and Sub-deacons read aloud in the church the teachings of the prophets and apostles: after this "lesson," the choir sing the "Gradual," which signifies progress in life; then the "Alleluia" is intoned, and this denotes spiritual joy; or in mournful offices the "Tract", expressive of spiritual sighing; for all these things ought to result from the aforesaid teaching. But the people are instructed "perfectly" by Christ's teaching contained in the Gospel, which is read by the higher ministers, that is, by the Deacons. And because we believe Christ as the Divine truth, according to John 8:46, "If I tell you the truth, why do you not believe Me?" after the Gospel has been read, the "Creed" is sung in which the people show that they assent by faith to Christ's doctrine. And it is sung on those festivals of which mention is made therein, as on the festivals of Christ, of the Blessed Virgin, and of the apostles, who laid the foundations of this faith, and on other such days.
So then, after the people have been prepared and instructed, the next step is to proceed to the celebration of the mystery, which is both offered as a sacrifice, and consecrated and received as a sacrament: since first we have the oblation; then the consecration of the matter offered; and thirdly, its reception.
In regard to the oblation, two things are done, namely, the people's praise in singing the "offertory," expressing the joy of the offerers, and the priest's prayer asking for the people's oblation to be made acceptable to God. Hence David said (1 Chronicles 29:17): "In the simplicity of my heart, I have... offered all these things: and I have seen with great joy Thy people which are here present, offer Thee their offerings": and then he makes the following prayer: "O Lord God... keep... this will."
Then, regarding the consecration, performed by supernatural power, the people are first of all excited to devotion in the "Preface," hence they are admonished "to lift up their hearts to the Lord," and therefore when the "Preface" is ended the people devoutly praise Christ's Godhead, saying with the angels: "Holy, Holy, Holy"; and His humanity, saying with the children: "Blessed is he that cometh." In the next place the priest makes a "commemoration," first of those for whom this sacrifice is offered, namely, for the whole Church, and "for those set in high places" (1 Timothy 2:2), and, in a special manner, of them "who offer, or for whom the mass is offered." Secondly, he commemorates the saints, invoking their patronage for those mentioned above, when he says: "Communicating with, and honoring the memory," etc. Thirdly, he concludes the petition when he says: "Wherefore that this oblation," etc., in order that the oblation may be salutary to them for whom it is offered.
Then he comes to the consecration itself. Here he asks first of all for the effect of the consecration, when he says: "Which oblation do Thou, O God," etc. Secondly, he performs the consecration using our Saviour's words, when he says: "Who the day before," etc. Thirdly, he makes excuse for his presumption in obeying Christ's command, saying: "Wherefore, calling to mind," etc. Fourthly, he asks that the sacrifice accomplished may find favor with God, when he says: "Look down upon them with a propitious," etc. Fifthly, he begs for the effect of this sacrifice and sacrament, first for the partakers, saying: "We humbly beseech Thee"; then for the dead, who can no longer receive it, saying: "Be mindful also, O Lord," etc.; thirdly, for the priests themselves who offer, saying: "And to us sinners," etc.
Then follows the act of receiving the sacrament. First of all, the people are prepared for Communion; first, by the common prayer of the congregation, which is the Lord's Prayer, in which we ask for our daily bread to be given us; and also by private prayer, which the priest puts up specially for the people, when he says: "Deliver us, we beseech Thee, O Lord," etc. Secondly, the people are prepared by the "Pax" which is given with the words, "Lamb of God," etc., because this is the sacrament of unity and peace, as stated above (73, 4; 79, 1). But in masses for the dead, in which the sacrifice is offered not for present peace, but for the repose of the dead, the "Pax" is omitted.
Then follows the reception of the sacrament, the priest receiving first, and afterwards giving it to others, because, as Dionysius says (Eccl. Hier. iii), he who gives Divine things to others, ought first to partake thereof himself.
Finally, the whole celebration of mass ends with the thanksgiving, the people rejoicing for having received the mystery (and this is the meaning of the singing after the Communion); and the priest returning thanks by prayer, as Christ, at the close of the supper with His disciples, "said a hymn" (Matthew 26:30).
Reply to Objection 1. The consecration is accomplished by Christ's words only; but the other words must be added to dispose the people for receiving it, as stated above.
Reply to Objection 2. As is stated in the last chapter of John (verse 25), our Lord said and did many things which are not written down by the Evangelists; and among them is the uplifting of His eyes to heaven at the supper; nevertheless the Roman Church had it by tradition from the apostles. For it seems reasonable that He Who lifted up His eyes to the Father in raising Lazarus to life, as related in John 11:41, and in the prayer which He made for the disciples (John 17:1), had more reason to do so in instituting this sacrament, as being of greater import.
The use of the word "manducate" instead of "comedite" makes no difference in the meaning, nor does the expression signify, especially since those words are no part of the form, as stated above (78, 1, ad 2,4).
The additional word "all" is understood in the Gospels, although not expressed, because He had said (John 6:54): "Except you eat the flesh of the Son of Man... you shall not have life in you."
Reply to Objection 3. The Eucharist is the sacrament of the unity of the whole Church: and therefore in this sacrament, more than in the others, mention ought to be made of all that belongs to the salvation of the entire Church.
Reply to Objection 4. There is a twofold instruction in the Faith: the first is for those receiving it for the first time, that is to say, for catechumens, and such instruction is given in connection with Baptism. The other is the instruction of the faithful who take part in this sacrament; and such instruction is given in connection with this sacrament. Nevertheless catechumens and unbelievers are not excluded therefrom. Hence in De Consecr., dist. 1, it is laid down: "Let the bishop hinder no one from entering the church, and hearing the word of God, be they Gentiles, heretics, or Jews, until the mass of the Catechumens begins," in which the instruction regarding the Faith is contained.
Reply to Objection 5. Greater devotion is required in this sacrament than in the others, for the reason that the entire Christ is contained therein. Moreover, this sacrament requires a more general devotion, i.e. on the part of the whole people, since for them it is offered; and not merely on the part of the recipients, as in the other sacraments. Hence Cyprian observes (De Orat. Domin. 31), "The priest, in saying the Preface, disposes the souls of the brethren by saying, 'Lift up your hearts,' and when the people answer--'We have lifted them up to the Lord,' let them remember that they are to think of nothing else but God."
Reply to Objection 6. As was said above (ad 3), those things are mentioned in this sacrament which belong to the entire Church; and consequently some things which refer to the people are sung by the choir, and same of these words are all sung by the choir, as though inspiring the entire people with them; and there are other words which the priest begins and the people take up, the priest then acting as in the person of God; to show that the things they denote have come to the people through Divine revelation, such as faith and heavenly glory; and therefore the priest intones the "Creed" and the "Gloria in excelsis Deo." Other words are uttered by the ministers, such as the doctrine of the Old and New Testament, as a sign that this doctrine was announced to the peoples through ministers sent by God. And there are other words which the priest alone recites, namely, such as belong to his personal office, "that he may offer up gifts and prayers for the people" (Hebrews 5:1). Some of these, however, he says aloud, namely, such as are common to priest and people alike, such as the "common prayers"; other words, however, belong to the priest alone, such as the oblation and the consecration; consequently, the prayers that are said in connection with these have to be said by the priest in secret. Nevertheless, in both he calls the people to attention by saying: "The Lord be with you," and he waits for them to assent by saying "Amen." And therefore before the secret prayers he says aloud, "The Lord be with you," and he concludes, "For ever and ever." Or the priest secretly pronounces some of the words as a token that regarding Christ's Passion the disciples acknowledged Him only in secret.
Reply to Objection 7. The efficacy of the sacramental words can be hindered by the priest's intention. Nor is there anything unbecoming in our asking of God for what we know He will do, just as Christ (John 17:1-5) asked for His glorification.
But the priest does not seem to pray there for the consecration to be fulfilled, but that it may be fruitful in our regard, hence he says expressively: "That it may become 'to us' the body and the blood." Again, the words preceding these have that meaning, when he says: "Vouchsafe to make this oblation blessed," i.e. according to Augustine (Paschasius, De Corp. et Sang. Dom. xii), "that we may receive a blessing," namely, through grace; "'enrolled,' i.e. that we may be enrolled in heaven; 'ratified,' i.e. that we may be incorporated in Christ; 'reasonable,' i.e. that we may be stripped of our animal sense; 'acceptable,' i.e. that we who in ourselves are displeasing, may, by its means, be made acceptable to His only Son."
Reply to Objection 8. Although this sacrament is of itself preferable to all ancient sacrifices, yet the sacrifices of the men of old were most acceptable to God on account of their devotion. Consequently the priest asks that this sacrifice may be accepted by God through the devotion of the offerers, just as the former sacrifices were accepted by Him.
Reply to Objection 9. The priest does not pray that the sacramental species may be borne up to heaven; nor that Christ's true body may be borne thither, for it does not cease to be there; but he offers this prayer for Christ's mystical body, which is signified in this sacrament, that the angel standing by at the Divine mysteries may present to God the prayers of both priest and people, according to Apocalypse 8:4: "And the smoke of the incense of the prayers of the saints ascended up before God, from the hand of the angel." But God's "altar on high" means either the Church triumphant, unto which we pray to be translated, or else God Himself, in Whom we ask to share; because it is said of this altar (Exodus 20:26): "Thou shalt not go up by steps unto My altar, i.e. thou shalt make no steps towards the Trinity." Or else by the angel we are to understand Christ Himself, Who is the "Angel of great counsel" (Isaiah 9:6: Septuagint), Who unites His mystical body with God the Father and the Church triumphant.
And from this the mass derives its name [missa; because the priest sends [mittit] his prayers up to God through the angel, as the people do through the priest. or else because Christ is the victim sent [missa] to us: accordingly the deacon on festival days "dismisses" the people at the end of the mass, by saying: "Ite, missa est," that is, the victim has been sent [missa est] to God through the angel, so that it may be accepted by God.
Source: Summa Theologica (New Advent)