Objection 1. It seems that this is not the proper form for the consecration of the wine. "This is the chalice of My blood, of the New and Eternal Testament, the Mystery of Faith, which shall be shed for you and for many unto the forgiveness of sins." For as the bread is changed by the power of consecration into Christ's body, so is the wine changed into Christ's blood, as is clear from what was said above (76, 1,2,3). But in the form of the consecration of the bread, the body of Christ is expressly mentioned, without any addition. Therefore in this form the blood of Christ is improperly expressed in the oblique case, and the chalice in the nominative, when it is said: "This is the chalice of My blood."
Objection 2. Further, the words spoken in the consecration of the bread are not more efficacious than those spoken in the consecration of the wine, since both are Christ's words. But directly the words are spoken--"This is My body," there is perfect consecration of the bread. Therefore, directly these other words are uttered--"This is the chalice of My blood," there is perfect consecration of the blood; and so the words which follow do not appeal to be of the substance of the form, especially since they refer to the properties of this sacrament.
Objection 3. Further, the New Testament seems to be an internal inspiration, as is evident from the Apostle quoting the words of Jeremias (31:31): "I will perfect unto the house of Israel a New Testament... I will give My laws into their mind" (Hebrews 8:8). But a sacrament is an outward visible act. Therefore, in the form of the sacrament the words "of the New Testament" are improperly added.
Objection 4. Further, a thing is said to be new which is near the beginning of its existence. But what is eternal has no beginning of its existence. Therefore it is incorrect to say "of the New and Eternal," because it seems to savor of a contradiction.
Objection 5. Further, occasions of error ought to be withheld from men, according to Isaiah 57:14: "Take away the stumbling blocks out of the way of My people." But some have fallen into error in thinking that Christ's body and blood are only mystically present in this sacrament. Therefore it is out of place to add "the mystery of faith."
Objection 6. Further, it was said above (73, 3, ad 3), that as Baptism is the sacrament of faith, so is the Eucharist the sacrament of charity. Consequently, in this form the word "charity" ought rather to be used than "faith."
Objection 7. Further, the whole of this sacrament, both as to body and blood, is a memorial of our Lord's Passion, according to 1 Corinthians 11:26: "As often as you shall eat this bread and drink the chalice, you shall show the death of the Lord." Consequently, mention ought to be made of Christ's Passion and its fruit rather in the form of the consecration of the blood, than in the form of the consecration of the body, especially since our Lord said: "This is My body, which shall be delivered up for you" (Luke 22:19).
Objection 8. Further, as was already observed (48, 2; 49, 3), Christ's Passion sufficed for all; while as to its efficacy it was profitable for many. Therefore it ought to be said: "Which shall be shed for all," or else "for many," without adding, "for you."
Objection 9. Further, the words whereby this sacrament is consecrated draw their efficacy from Christ's institution. But no Evangelist narrates that Christ spoke all these words. Therefore this is not an appropriate form for the consecration of the wine.
On the contrary, The Church, instructed by the apostles, uses this form.
I answer that, There is a twofold opinion regarding this form. Some have maintained that the words "This is the chalice of My blood" alone belong to the substance of this form, but not those words which follow. Now this seems incorrect, because the words which follow them are determinations of the predicate, that is, of Christ's blood. Consequently they belong to the integrity of the expression.
And on this account others say more accurately that all the words which follow are of the substance of the form down to the words, "As often as ye shall do this," which belong to the use of this sacrament, and consequently do not belong to the substance of the form. Hence it is that the priest pronounces all these words, under the same rite and manner, namely, holding the chalice in his hands. Moreover, in Luke 22:20, the words that follow are interposed with the preceding words: "This is the chalice, the new testament in My blood."
Consequently it must be said that all the aforesaid words belong to the substance of the form; but that by the first words, "This is the chalice of My blood," the change of the wine into blood is denoted, as explained above (Article 2) in the form for the consecration of the bread; but by the words which come after is shown the power of the blood shed in the Passion, which power works in this sacrament, and is ordained for three purposes. First and principally for securing our eternal heritage, according to Hebrews 10:19: "Having confidence in the entering into the holies by the blood of Christ"; and in order to denote this, we say, "of the New and Eternal Testament." Secondly, for justifying by grace, which is by faith according to Romans 3:25-26: "Whom God hath proposed to be a propitiation, through faith in His blood... that He Himself may be just, and the justifier of him who is of the faith of Jesus Christ": and on this account we add, "The Mystery of Faith." Thirdly, for removing sins which are the impediments to both of these things, according to Hebrews 9:14: "The blood of Christ... shall cleanse our conscience from dead works," that is, from sins; and on this account, we say, "which shall be shed for you and for many unto the forgiveness of sins."
Reply to Objection 1. The expression "This is the chalice of My blood" is a figure of speech, which can be understood in two ways. First, as a figure of metonymy; because the container is put for the contained, so that the meaning is: "This is My blood contained in the chalice"; of which mention is now made, because Christ's blood is consecrated in this sacrament, inasmuch as it is the drink of the faithful, which is not implied under the notion of blood; consequently this had to be denoted by the vessel adapted for such usage. Secondly, it can be taken by way of metaphor, so that Christ's Passion
is understood by the chalice by way of comparison, because, like a cup, it inebriates, according to Lamentations 3:15: "He hath filled me with bitterness, he hath inebriated me with wormwood": hence our Lord Himself spoke of His Passion as a chalice, when He said (Matthew 26:39): "Let this chalice pass away from Me": so that the meaning is: "This is the chalice of My Passion." This is denoted by the blood being consecrated apart from the body; because it was by the Passion that the blood was separated from the body.
Reply to Objection 2. As was said above (ad 1; 76, 2, ad 1), the blood consecrated apart expressly represents Christ's Passion, and therefore mention is made of the fruits of the Passion in the consecration of the blood rather than in that of the body, since the body is the subject of the Passion. This is also pointed out in our Lord's saying, "which shall be delivered up for you," as if to say, "which shall undergo the Passion for you."
Reply to Objection 3. A testament is the disposal of a heritage. But God disposed of a heavenly heritage to men, to be bestowed through the virtue of the blood of Jesus Christ; because, according to Hebrews 9:16: "Where there is a testament the death of the testator must of necessity come in." Now Christ's blood was exhibited to men in two ways. First of all in figure, and this belongs to the Old Testament; consequently the Apostle concludes (Hebrews 9:16): "Whereupon neither was the first indeed dedicated without blood," which is evident from this, that as related in Exodus 24:7-8, "when every" commandment of the law "had been read" by Moses, "he sprinkled all the people" saying: "This is the blood of the testament which the Lord hath enjoined unto you."
Secondly, it was shown in very truth; and this belongs to the New Testament. This is what the Apostle premises when he says (Romans 9:15): "Therefore He is the Mediator of the New Testament, that by means of His death... they that are called may receive the promise of eternal inheritance." Consequently, we say here, "The blood of the New Testament," because it is shown now not in figure but in truth; and therefore we add, "which shall be shed for you." But the internal inspiration has its origin in the power of this blood, according as we are justified by Christ's Passion.
Reply to Objection 4. This Testament is a "new one" by reason of its showing forth: yet it is called "eternal" both on account of God's eternal pre-ordination, as well as on account of the eternal heritage which is prepared by this testament. Moreover, Christ's Person is eternal, in Whose blood this testament is appointed.
Reply to Objection 5. The word "mystery" is inserted, not in order to exclude reality, but to show that the reality is hidden, because Christ's blood is in this sacrament in a hidden manner, and His Passion was dimly foreshadowed in the Old Testament.
Reply to Objection 6. It is called the "Sacrament of Faith," as being an object of faith: because by faith alone do we hold the presence of Christ's blood in this sacrament. Moreover Christ's Passion justifies by faith. Baptism is called the "Sacrament of Faith" because it is a profession of faith. This is called the "Sacrament of Charity," as being figurative and effective thereof.
Reply to Objection 7. As stated above (ad 2), the blood consecrated apart represents Christ's blood more expressively; and therefore mention is made of Christ's Passion and its fruits, in the consecration of the blood rather than in that of the body.
Reply to Objection 8. The blood of Christ's Passion has its efficacy not merely in the elect among the Jews, to whom the blood of the Old Testament was exhibited, but also in the Gentiles; nor only in priests who consecrate this sacrament, and in those others who partake of it; but likewise in those for whom it is offered. And therefore He says expressly, "for you," the Jews, "and for many," namely the Gentiles; or, "for you" who eat of it, and "for many," for whom it is offered.
Reply to Objection 9. The Evangelists did not intend to hand down the forms of the sacraments, which in the primitive Church had to be kept concealed, as Dionysius observes at the close of his book on the ecclesiastical hierarchy; their object was to write the story of Christ. Nevertheless nearly all these words can be culled from various passages of the Scriptures. Because the words, "This is the chalice," are found in Luke 22:20, and 1 Corinthians 11:25, while Matthew says in 26:28: "This is My blood of the New Testament, which shall be shed for many unto the remission of sins." The words added, namely, "eternal" and "mystery of faith," were handed down to the Church by the apostles, who received them from our Lord, according to 1 Corinthians 11:23: "I have received of the Lord that which also I delivered unto you."
Source: Summa Theologica (New Advent)