Objection 2: Further, men are united with Christ through this sacrament as the members with the head. But Christ is the Head of all men, even of those who have existed from the beginning of the world, as stated above (Q[8], AA[3],6). Therefore the institution of this sacrament should not have been postponed till the Lord's supper.
Objection 3: Further, this sacrament is called the memorial of our Lord's Passion, according to Mat. 26 ( Lk. 22:19 ): "Do this for a commemoration of Me." But a commemoration is of things past. Therefore, this sacrament should not have been instituted before Christ's Passion.
Objection 4: Further, a man is prepared by Baptism for the Eucharist, which ought to be given only to the baptized. But Baptism was instituted by Christ after His Passion and Resurrection, as is evident from Mat. 28:19. Therefore, this sacrament was not suitably instituted before Christ's Passion.
On the contrary, This sacrament was instituted by Christ, of Whom it is said ( Mk. 7:37 ) that "He did all things well."
I answer that, This sacrament was appropriately instituted at the supper, when Christ conversed with His disciples for the last time. First of all, because of what is contained in the sacrament: for Christ is Himself contained in the Eucharist sacramentally. Consequently, when Christ was going to leave His disciples in His proper species, He left Himself with them under the sacramental species; as the Emperor's image is set up to be reverenced in his absence. Hence Eusebius says: "Since He was going to withdraw His assumed body from their eyes, and bear it away to the stars, it was needful that on the day of the supper He should consecrate the sacrament of His body and blood for our sakes, in order that what was once offered up for our ransom should be fittingly worshiped in a mystery."
Secondly, because without faith in the Passion there could never be any salvation, according to Rom. 3:25 : "Whom God hath proposed to be a propitiation, through faith in His blood." It was necessary accordingly that there should be at all times among men something to show forth our Lord's Passion; the chief sacrament of which in the old Law was the Paschal Lamb. Hence the Apostle says ( 1 Cor. 5:7 ): "Christ our Pasch is sacrificed." But its successor under the New Testament is the sacrament of the Eucharist, which is a remembrance of the Passion now past, just as the other was figurative of the Passion to come. And so it was fitting that when the hour of the Passion was come, Christ should institute a new Sacrament after celebrating the old, as Pope Leo I says (Serm. lviii).
Thirdly, because last words, chiefly such as are spoken by departing friends, are committed most deeply to memory; since then especially affection for friends is more enkindled, and the things which affect us most are impressed the deepest in the soul. Consequently, since, as Pope Alexander I says, "among sacrifices there can be none greater than the body and blood of Christ, nor any more powerful oblation"; our Lord instituted this sacrament at His last parting with His disciples, in order that it might be held in the greater veneration. And this is what Augustine says (Respons. ad Januar. i): "In order to commend more earnestly the death of this mystery, our Saviour willed this last act to be fixed in the hearts and memories of the disciples whom He was about to quit for the Passion."
Reply to Objection 1: We are nourished from the same things of which we are made, but they do not come to us in the same way; for those out of which we are made come to us through generation, while the same, as nourishing us, come to us through being eaten. Hence, as we are new-born in Christ through Baptism, so through the Eucharist we eat Christ.
Reply to Objection 2: The Eucharist is the perfect sacrament of our Lord's Passion, as containing Christ crucified; consequently it could not be instituted before the Incarnation; but then there was room for only such sacraments as were prefigurative of the Lord's Passion.
Reply to Objection 3: This sacrament was instituted during the supper, so as in the future to be a memorial of our Lord's Passion as accomplished. Hence He said expressively: "As often as ye shall do these things" [*Cf. Canon of the Mass], speaking of the future.
Reply to Objection 4: The institution responds to the order of intention. But the sacrament of the Eucharist, although after Baptism in the receiving, is yet previous to it in intention; and therefore it behooved to be instituted first. or else it can be said that Baptism was already instituted in Christ's Baptism; hence some were already baptized with Christ's Baptism, as we read in Jn. 3:22.
Whether the Paschal Lamb was the chief figure of this sacrament?
Objection 1: It seems that the Paschal Lamb was not the chief figure of this sacrament, because ( Ps. 109:4 ) Christ is called "a priest according to the order of Melchisedech," since Melchisedech bore the figure of Christ's sacrifice, in offering bread and wine. But the expression of likeness causes one thing to be named from another. Therefore, it seems that Melchisedech's offering was the "principal" figure of this sacrament.
Objection 2: Further, the passage of the Red Sea was a figure of Baptism, according to 1 Cor. 10:2 : "All . . . were baptized in the cloud and in the sea." But the immolation of the Paschal Lamb was previous to the passage of the Red Sea, and the Manna came after it, just as the Eucharist follows Baptism. Therefore the Manna is a more expressive figure of this sacrament than the Paschal Lamb.
Objection 3: Further, the principal power of this sacrament is that it brings us into the kingdom of heaven, being a kind of "viaticum." But this was chiefly prefigured in the sacrament of expiation when the "high-priest entered once a year into the Holy of Holies with blood," as the Apostle proves in Heb. 9 . Consequently, it seems that that sacrifice was a more significant figure of this sacrament than was the Paschal Lamb.
On the contrary, The Apostle says ( 1 Cor. 5:7 , 8 ): "Christ our Pasch is sacrificed; therefore let us feast . . . with the unleavened bread of sincerity and truth."
I answer that, We can consider three things in this sacrament: namely, that which is sacrament only, and this is the bread and wine; that which is both reality and sacrament, to wit, Christ's true body; and lastly that which is reality only, namely, the effect of this sacrament. Consequently, in relation to what is sacrament only, the chief figure of this sacrament was the oblation of Melchisedech, who offered up bread and wine. In relation to Christ crucified, Who is contained in this sacrament, its figures were all the sacrifices of the Old Testament, especially the sacrifice of expiation, which was the most solemn of all. While with regard to its effect, the chief figure was the Manna, "having in it the sweetness of every taste" ( Wis. 16:20 ), just as the grace of this sacrament refreshes the soul in all respects.
The Paschal Lamb foreshadowed this sacrament in these three ways. First of all, because it was eaten with unleavened loaves, according to Ex. 12:8 : "They shall eat flesh . . . and unleavened bread." As to the second because it was immolated by the entire multitude of the children of Israel on the fourteenth day of the moon; and this was a figure of the Passion of Christ, Who is called the Lamb on account of His innocence. As to the effect, because by the blood of the Paschal Lamb the children of Israel were preserved from the destroying Angel, and brought from the Egyptian captivity; and in this respect the Paschal Lamb is the chief figure of this sacrament, because it represents it in every respect.
From this the answer to the Objections is manifest.