11 Therefore “this meat, not that which perishes, but that which endures unto everlasting life, which the Son of man shall give unto you; for Him has God the Father sealed.” Do not take this Son of man as you take other sons of men, of whom it is said, “And the sons of men will trust in the protection of Your wings.” This Son of man is separated by a certain grace of the spirit; Son of man according to the flesh, taken out from the number of men: He is the Son of man. This Son of man is also the Son of God; this man is even God. In another place, when questioning His disciples, He says: “Whom do men say that I, the Son of man, am? And they answered, Some John, some Elias, some Jeremias, or one of the prophets. And He said unto them, But whom say ye that I am? Peter answered, You are the Christ, the Son of the living God.” He declared Himself Son of man, Peter declared Him the Son of the living God. Most fitly did He mention that which in mercy He had manifested Himself to be; most fitly did the other mention that which He continues to be in glory. The Word of God commends to our attention His own humility: the man acknowledged the glory of his Lord. And indeed, brethren, I think that this is just. He humbled Himself for us, let us glorify Him. For not for Himself is He Son of man, but for us. Therefore was He Son of man in that way, when “the Word was made flesh, and dwelt among us.” For to that end “God the Father sealed Him.” What is to seal, but to put some particular mark? To seal is to impress some mark which cannot be confounded with the rest. To seal is to put a mark on a thing. When you put a mark on anything, you do so lest it might be confused with other things, and you should not be able to recognize it. “The Father,” then, “has sealed Him.” What is that, “has sealed”? Bestowed on Him something peculiar, which puts Him out of comparison with all other men. For that reason it is said of Him, “God, even Your God, has anointed You with the oil of gladness above Your fellows.” What is it then to seal, but to have Him excepted? This is the import of “above Your fellows.” And so, do not, says He, despise me because I am the Son of man, but seek from me, “not the meat that perishes, but that which endures to eternal life.” For I am the Son of man in such manner as not to be one of you: I am Son of man in such manner that God the Father sealed me. What does that mean, He “sealed me”? Gave me something peculiarly my own, that I should not be confounded with mankind, but that mankind should be delivered by me.
12. “They said therefore unto Him, What shall we do, that we may work the works of God?” For He had said to them, “Labor not for the meat which perishes, but for that which endures unto eternal life.” “What shall we do?” they ask; by observing what, shall we be able to fulfill this precept? “Jesus answered and said unto them, This is the work of God, that you believe in Him whom He has sent.” This is then to eat the meat, not that which perishes, but that which endures unto eternal life. To what purpose do you make ready teeth and stomach? Believe, and you have eaten already. Faith is indeed distinguished from works, even as the apostle says, “that a man is justified by faith without the works of the law:” there are works which appear good, without faith in Christ; but they are not good, because they are not referred to that end in which works are good; “for Christ is the end of the law for righteousness to every one that believes.” For that reason, He wills not to distinguish faith from work, but declared faith itself to be work. For it is that same faith that works by love. Nor did He say, This is your work; but, “This is the work of God, that you believe in Him whom He has sent;” so that he who glories, may glory in the Lord. And because He invited them to faith, they, on the other hand, were still asking for signs by which they might believe. See if the Jews do not ask for signs. “They said therefore unto Him, What sign will you do, that we may see and believe you? What do you work?” Was it a trifle that they were fed with five loaves? They knew this indeed, but they preferred manna from heaven to this food. But the Lord Jesus declared Himself to be such an one, that He was superior to Moses. For Moses dared not say of himself that ge gave, “not the meat which perishes, but that which endures to eternal life.” Jesus promised something greater than Moses gave. By Moses indeed was promised a kingdom, and a land flowing with milk and honey, temporal peace, abundance of children, health of body, and all other things, temporal goods indeed, yet in figure spiritual; because in the Old Testament they were promised to the old man. They considered therefore the things promised by Moses, and they considered the things promised by Christ. The former promised a full belly on the earth, but of the meat which perishes; the latter promised, “not the meat which perishes, but that which endures unto eternal life.” They gave attention to Him that promised the more, but just as if they did not yet see Him do greater things. They considered therefore what sort of works Moses had done, and they wished yet some greater works to be done by Him who promised them such great things. What, say they, will you do, that we may believe you? And that you may know that they compared those former miracles with this and so judged these miracles which Jesus did as being less; “Our fathers,” say they, “did eat manna in the wilderness.” But what is manna? Perhaps ye despise it. “As it is written, He gave them manna to eat.” By Moses our fathers received bread from heaven, and Moses did not say to them, “Labor for the meat which perishes not.” You promise “meat which perishes not, but which endures to eternal life;” and yet you work not such works as Moses did. He gave, not barley loaves, but manna from heaven.
13. “Then Jesus said unto them, Verily, verily, I say unto you, not Moses gave you bread from heaven, but my Father gave you bread from heaven. For the true bread is He that comes down from heaven, and gives life to the world.” The true bread then is He that gives life to the world; and the same is the meat of which I have spoken a little before—“Labor not for the meat which perishes, but for that which endures unto eternal life.” Therefore, both that manna signified this meat, and all those signs were signs of me. You have longed for signs of me; do ye despise Him that was signified? Not Moses then gave bread from heaven: God gives bread. But what bread? Manna, perhaps? No, but the bread which manna signified, namely, the Lord Jesus Himself. My Father gives you the true bread. “For the bread of God is He that comes down from heaven, and gives life to the world. Then said they unto Him, Lord, evermore give us this bread.” Like that Samaritan woman, to whom it was said, “Whoso drinks of this water shall never thirst.” She, immediately understanding it in reference to the body, and wishing to be rid of want, said, “Give me, O Lord, of this water;” in the same manner also these said, “O Lord, give us this bread;” which may refresh us, and yet not fail.
Source: Tractates on the Gospel of John (New Advent)