With no disrespect toward the Angelic Doctor, the Form of the Eucharist should be as follows:
Form To Be Used In The Consecration Of The Bread
We are then taught by the holy Evangelists, Matthew and Luke, and also by the Apostle, that the form consists of these words: This is my body; for it is written: Whilst they were at supper, Jesus took bread, and blessed it, and brake, and gave to his disciples, and said: Take and eat, This is my body.
This form of consecration having been observed by Christ the Lord has been always used by the Catholic Church. ...
Not All The Words Used Are Essential
Although in the Evangelist the words, Take and eat, precede the words (This is my body),...they are not necessary to the validity of the Sacrament,...
Form To Be Used In The Consecration Of The Wine
With regard to the consecration of the wine,...We are then firmly to believe that it consists in the following words: 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, to the remission of sins. Of these words the greater part are taken from Scripture; but some have been preserved in the Church from Apostolic tradition.
Thus the words, this is the chalice, are found in St. Luke and in the Apostle; but the words that immediately follow, of my blood, or my blood of the new testament, which shall be shed for you and for many to the remission of sins, are found partly in St. Luke and partly in St. Matthew. But the words, eternal, and the mystery of faith, have been taught us by holy tradition, the interpreter and keeper of Catholic truth.
Concerning this form no one can doubt, if he here also attend to what has been already said about the form used in the consecration of the bread. The form to be used (in the consecration) of this element, evidently consists of those words which signify that the substance of the wine is changed into the blood of our Lord. since, therefore, the words already cited clearly declare this, it is plain that no other words constitute the form.
They moreover express certain admirable fruits of the blood shed in the Passion of our Lord, fruits which pertain in a most special manner to this Sacrament. Of these, one is access to the eternal inheritance, which has come to us by right of the new and everlasting testament. Another is access to righteousness by the mystery of faith; for God hath set forth Jesus to be a propitiator through faith in his blood, that he himself may be just, and the justifier of him, who is of the faith of Jesus. Christ. A third effect is the remission of sins.
Explanation Of The Form Used In The Consecration Of The Wine
Since these very words of consecration are replete with mysteries and most appropriately suitable to the subject, they demand a more minute consideration.
The words: This is the chalice of my blood, are to be understood to mean: This is my blood, which is contained in this chalice. The mention of the chalice made at the consecration of the blood is right and appropriate, inasmuch as the blood is the drink of the faithful, and this would not be sufficiently signified if it were not contained in some drinking vessel.
Next follow the words: Of the new testament. These have been added that we might understand the blood of Christ the Lord to be given not under a figure, as was done in the Old Law, of which we read in the Epistle to the Hebrews that without blood a testament is not dedicated; but to be given to men in truth and in reality, as becomes the New Testament. Hence the Apostle says: Christ therefore is the mediator of the new testament, that by means of his death, they who are called may receive the promise of eternal inheritance.
The word eternal refers to the eternal inheritance, the right to which we acquire by the death of Christ the Lord, the eternal testator.
The words mystery of faith, which are subjoined, do not exclude the reality, but signify that what lies hidden and concealed and far removed from the perception of the eye, is to be believed with firm faith. In this passage, however, these words bear a meaning different from that which they have when applied also to Baptism. Here the mystery of faith consists in seeing by faith the blood of Christ veiled under the species of wine; but Baptism is justly called by us the Sacrament of faith, by the Greeks, the mystery of faith, because it embraces the entire profession of the Christian faith.
Another reason why we call the blood of the Lord the mystery of faith is that human reason is particularly beset with difficulty and embarrassment when faith proposes to our belief that Christ the Lord, the true Son of God, at once God and man, suffered death for us, and this death is designated by the Sacrament of His blood.
Here, therefore, rather than at the consecration of His body, is appropriately commemorated the Passion of our Lord, by the words. which shall be shed for the remission of sins. For the blood, separately consecrated, serves to place before the eyes of all, in a more forcible manner, the Passion of our Lord, His death, and the nature of His sufferings.
The additional words for you and for many, are taken, some from Matthew, some from Luke, but were joined together by the Catholic Church under the guidance of the Spirit of God. They serve to declare the fruit and advantage of His Passion. For if we look to its value, we must confess that the Redeemer shed His blood for the salvation of all; but if we look to the fruit which mankind have received from it, we shall easily find that it pertains not unto all, but to many of the human race. When therefore ('our Lord) said: For you, He meant either those who were present, or those chosen from among the Jewish people, such as were, with the exception of Judas, the disciples with whom He was speaking. When He added, And for many, He wished to be understood to mean the remainder of the elect from among the Jews or Gentiles.
With reason, therefore, were the words for all not used, as in this place the fruits of the Passion are alone spoken of, and to the elect only did His Passion bring the fruit of salvation. And this is the purport of the Apostle when he says: Christ was offered once to exhaust the sins of many; and also of the words of our Lord in John: I pray for them; I pray not for the world, but for them whom thou hast given me, because they are thine.
Beneath the words of this consecration lie hid many other mysteries, which by frequent meditation and study of sacred things, pastors will find it easy, with the divine assistance, to discover for themselves.
Catechism of the Council of TRENT.