24 Verily, verily, I say unto you, Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit.
[AD 407] John Chrysostom on John 12:20-26
(Hom. lxvi. 2) The time being now near, when they would be made proselytes. They hear Christ talked of, and wish to see Him: The same came therefore to Philip, which was of Bethsaida of Galilee, and desired him, saying, Sir, we would see Jesus.

(Hom. lxvii. 2) As being the elder disciple. He had heard our Saviour say, Go not into the way of the Gentiles; (Matt. 10:5) and therefore he communicates with his fellow-disciple, and they refer the matter to their Lord: And again Andrew and Philip tell Jesus.

(Hom. lxvi. 2) He illustrates His discourse by an example from nature. A grain of corn produces fruit, after it has died. How much more then must the Son of God? The Gentiles were to be called after the Jews had finally offended; i. e. after His crucifixion. Now then that the Gentiles of their own accord offered their faith, He saw that His crucifixion could not be far off. And to console the sorrow of His disciples, which He foresaw would arise, He tells them that to bear patiently not only His death, but their own too, is the only way to good: He that loveth his life shall lose it.

(Hom. lxvii. 1) He loveth his life in this world, who indulges its inordinate desires; he hateth it, who resists them. It is not, who doth not yield to, but, who hateth. For as we cannot bear to hear the voice or see the face of them whom we hate; so when the soul invites us to things contrary to God, we should turn her away from them with all our might.

(Hom. lxvii. 1) This present life is sweet to them who are given up to it. But he who looks heavenwards, and sees what good things are there, soon despises this life. When the better life appears, the worse is despised. This is Christ's meaning, when He says, If any man serve Me, let him follow Me, i. e. imitate Me, both in My death, and life. For he who serves, should follow him whom he serves.

(Hom. lxvii) So then death will be followed by resurrection. Where I am, He says; for Christ was in heaven before His resurrection. Thither let us ascend in heart and in mind.
If any man serve Me, him will My Father honour. This must be understood as an explanation of the preceding. There also shall My servant be. For what greater honour can an adopted son receive than to be where the Only Son is?

(Hom. lxvii) He says, My Father will honour him, not, I will honour him; because they had not yet proper notions of His nature, and thought Him inferior to the Father.

[AD 430] Augustine of Hippo on John 12:20-26
(Tr. li. 8) Lo! the Jews wish to kill Him, the Gentiles to see Him. But they also were of the Jews who cried, Blessed is He that cometh in the name of the Lord. So behold them of the circumcision, and them of the uncircumcision, once so wide apart, coming together like two walls, and meeting in one faith of Christ by the kiss of peace.
Philip cometh and telleth Andrew.

(Tr. li. 8) Listen we to the voice of the corner stone: And Jesus answered them, saying, The hour is come, that the Son of man should be glorified. Did He think Himself glorified, because the Gentiles wished to see? No. But He saw that after His passion and resurrection, the Gentiles in all lands would believe on Him; and took occasion from this request of some Gentiles to see Him, to announce the approaching fulness of the Gentiles, for that the hour of His being glorified was now at hand, and that after He was glorified in the heavens, the Gentiles would believe; according to the passage in the Psalm, Set up Thyself, O God, above the heavens, and Thy glory above all the earth. (Ps. 56, and 107) But it was necessary that His exaltation and glory should be preceded by His humiliation and passion; wherefore He says, Verily, verily, I say unto you, Except a corn of wheat fall into they round and die, it abideth alone: but if it die, it bringeth forth much fruit. That corn was He; to be mortified in the unbelief of the Jews, to be multiplied in the faith of the Gentiles.

(Tr. li. 10) This may be understood in two ways: 1. If thou lovest it, lose it: if thou wouldest preserve thy life in Christ, fear not death for Christ. 2. Do not love thy life here, lest thou lose it hereafter. The latter seems to be the more evangelical (evangelicus) sense; for it follows, And he that hateth his life in this world, shall keep it unto life eternal.

(Tr. li. 10) But think not for an instant, that by hating thy soul, is meant that thou mayest kill thyself. For wicked and perverse men have sometimes so mistaken it, and have burnt and strangled themselves, thrown themselves from precipices, and in other ways put an end to themselves. This did not Christ teach; nay, when the devil tempted Him to cast Himself down, He said, Get thee hence, Satanb. But when no other choice is given thee; when the persecutor threatens death, and thou must either disobey God's law, or depart out of this life, then hate thy life in this world, that thou mayest keep it unto life eternal.

(Tr. li) But what is it to serve Christ? The very words explain. They serve Christ who seek not their own things, but the things of Jesus Christ, i. e. who follow Him, walk in His, not their own, ways, do all good works for Christ's sake, not only works of mercy to men's bodies, but all others, till at length they fulfil that great work of love, and lay down their lives for the brethren. But what fruit, what reward? you ask. The next words tell you: And where I am, there shall also My servant be. Love Him for His own sake, and think it a rich reward for thy service, to be with Him.

[AD 735] Bede on John 12:20-26
The temple at Jerusalem was so famous, that on the feast days, not only the people near, but many Gentiles from distant countries came to worship in it; as that eunuch of Candace, Queen of the Ethiopians, mentioned in the Acts. The Gentiles who were at Jerusalem now, had come up for this purpose: And there were certain Gentiles among them who came to worship at the feast.

He Himself, of the seed of the Patriarchs, was sown in the field of this world, that by dying, He might rise again with increase. He died alone; He rose again with many.

[AD 1107] Theophylact of Ohrid on John 12:20-26
As if they said, The more you attack Him, the more will His power and reputation increase. What use then of these attempts?

It were harsh to say that a man should hate his soul; so He adds, in this world: i. e. for a particular time, not for ever. And we shall gain in the end by so doing: shall keep it unto life eternal.

[AD 202] Irenaeus on John 12:24
A cutting from the vine planted in the ground bears fruit in its season, or a kernel of wheat falling into the earth and becoming decomposed rises and is multiplied by the Spirit of God, who contains all things. And then, through the wisdom of God, it serves for our use when, after receiving the Word of God, it becomes the Eucharist, which is the body and blood of Christ. In the same way our bodies, being nourished by it, and deposited in the earth and suffering decomposition there, shall rise at their appointed time. The Word of God grants them resurrection to the glory of God, even the Father who freely gives to this mortal immortality, and to this corruptible incorruption. This is so because the strength of God is made perfect in weakness14 in order that we may never become puffed up, as if we had life from ourselves, or become exalted against God with ungrateful minds.

[AD 397] Ambrose of Milan on John 12:24
How many more wonders appear, if you examine each plant, noticing how the seed when laid in the earth decays and, if it did not die, would bear no fruit. But when it decays, by that very act of death, it rises up to bear fruit in greater abundance. The pliable sod receives, then, a grain of wheat. The scattered seed is controlled by the use of the hoe, and mother earth cherishes it in firm embraces to her breast. When that grain decays, there comes the pleasing aspect of the green burgeoning shoot, which immediately reveals its kind from its similarity to its own seed, so that you may discover the nature of the plant even in the very beginning of its growth, and its fruit, too, is made evident to you.

[AD 428] Theodore of Mopsuestia on John 12:24
However, he says, my death must not upset you. As indeed a grain of wheat is just a single grain before falling into the earth, after it has fallen and decomposed, it sprouts forth in great glory and produces double fruit by showing before everyone its riches in its ears and displaying the spectacle of its beauty to those looking on. This is the same way you should think about me. Now I am alone, and just one more man among obscure people without any glory. But when I undergo the passion of the cross, I will be raised in great honor. And when I produce much fruit then everyone will know me—not only the Jews but also the people of the entire world will call me their Lord. Then, not even the spiritual powers will refuse to worship me.

[AD 444] Cyril of Alexandria on John 12:24
He not only foretells His suffering and the nearness of the time, but He also alleges the reason why He counted His suffering most precious, saying that the benefit of His passion would be great; for else He would not have chosen to suffer, for He suffered not unwillingly. For by reason of His clemency towards us, He displayed such great and tender kindness as deliberately to endure cruelties of all kinds for our sake. And even as a grain of wheat sown in the earth shoots forth many ears of corn, not receiving through them any loss to itself, but being present by its power in all the grains of every ear; for out of it they all shot forth: so also the Lord died, and opening the recesses of the earth, brought up with Himself the souls of men, Himself being in them all according to the doctrine of the faith, over and above His own separate and distinct existence. And it is not to the dead only that He has granted the power of receiving the fruits of the benefit He brings, but to the living also; if indeed the doctrine is made faithfully to correspond to the form of the parable. For the life of all men, both of dead and living, is a fruit of the sufferings of Christ. For the death of Christ became a seed of life.

Can it be then that the Divine Nature of the Word became capable of death? Surely it were altogether impious to say this. For the Word of God the Father is in His Nature Life: He raises to life, but He does not fall: He brings death to naught, He is not made subject to corruption: He quickens that which lacks life, but seeks not His own life from another. For even as light could not become darkness, so it is impossible that Life should cease to be life. How then is the same Person said to fall into the earth as a grain of wheat, and also to "go up" as "God with a shout?" Surely it is evident that to taste of death was fitting for Him, inasmuch as He became Man: but nevertheless to go up in the manner of God, was His own natural prerogative.
[AD 444] Cyril of Alexandria on John 12:24
Christ is also symbolized by a sheaf of grain, as a brief explanation will show.The human race may be compared with stalks of wheat in a field rising, as it were, from the earth, awaiting their full growth and development, and then in time being cut down by the reaper, which is death. The comparison is apt, since Christ himself spoke of our race in this way when he said to his holy disciples, “Do you not say, ‘Four months and it will be harvest time?’ Look at the fields; I tell you, they are already white and ready for harvesting. The reaper is already receiving his wages and bringing in a crop for eternal life.” …
Now Christ became like one of us. He sprang from the holy Virgin like a stalk of wheat from the ground. Indeed, he spoke of himself as a grain of wheat when he said, “I tell you truly, unless a grain of wheat falls into the ground and dies, it remains as it was, a single grain, but if it dies its yield is very great.” And so, like a sheaf of grain, the firstfruits, as it were, of the earth, he offered himself to the Father for our sake.
For we do not think of a stalk of wheat in isolation any more than we do of ourselves. We think of it rather as part of a sheaf, which is a single bundle made up of many stalks. The stalks have to be gathered into a bundle before they can be used, and this is the key to the mystery they represent, the mystery of Christ, who, though one, appears in the image of a sheaf to be made up of many, as in fact he is. Spiritually, he contains in himself all believers. “As we have been raised up with him,” writes Paul, “so we have also been enthroned with him in heaven.” He is a human being like ourselves, and this had made us one body with him, the body being the bond that unites us. We can say, therefore, that in him we are all one, and indeed he himself says to God, his heavenly Father, “It is my desire that as you and I are one, so they also may be one in us.”