John 6:58

As the living Father, &c.... hath sent Me, in the Flesh into the world, through the Incarnation, for the salvation of men. The living Father, who is Himself Divine Life, uncreated Substance, and therefore in begetting Me hath communicated to Me the same Substance, that I might communicate the same to the Humanity, which He sent Me to assume, that I might communicate similar spiritual, holy, blessed and eternal life to the faithful who eat of Me.

And I live because of (propter) the Father, i.e., through the Father, of the Father. For the Father in begetting Me communicates to Me His own Divinity, which is the essence of life. For God hath begotten God, the Living One hath begotten the Living One. "The Son therefore," saith Cyril, "is as Light of Light, and as Life of Life. And as the Father gives light through the Son to the things which need light, and through Him does wisely, so through the Son as through His life which proceeds from Him, He quickens those things which have need of life." And again, "I live by (propter) the Father: for since My Father is Life by nature, and because I am by nature His Son, I naturally possess this property of His nature, that is life."

Here Christ gives the reason by which He is living and quickening Bread in the Eucharist, who will raise us from death at the judgment-day. And He opens out the very origin and fountain of life and resurrection. For God the Father is that Fount of life, according to the words, "With Thee is the Fountain of life" (Psa 35:10). And He communicates together with His Essence this life to His Son, whereby it comes to pass that the Son Himself is a Fountain of Life. Wherefore as the Father always abides in the Son, always imparts this source of life to the Son, so also the Son, being sent by the Father in the flesh, and abiding in it, continually infuses this Divine life into the flesh and the Humanity which He has assumed, and continually abiding in us, inspires the like life into us who receive His Flesh in the Eucharist. He therefore shall live by Me, that as the Father communicates His own life to the Son, so Christ communicates His life to the Christian who rightly receives Him. Wherefore S. Dionysius the Areopagite (de Eccles. Hierarch. c. 1) teaches that the Priest passes into fellowship with the Godhead, and (c. 2) that communion deifies, and (c. 3) that those who worthily communicate are by the similitude of a pure and divine life grafted into Christ. Moreover, the Eucharist does the same thing for the pure and the penitent. Whence S. Augustine (Serm. 1 , de Temp.) says, "Let him change his life, who wishes to receive Life. For if he change not his life, he will receive Life unto condemnation, and will rather be destroyed than healed by It: rather slain than quickened." For the impure and the impenitent receive not life, but death of body and soul, both now and eternally, from the Eucharist. Thus S. Cyprian (Serm. 5, de Laps.), speaking of a woman who communicated unworthily, says, "She received not bread, but a sword, and as it were taking some deadly poison she was shaken, trembled, and fell. She who had deceived man, felt the vengeance of God." He relates several cases of a similar kind. Durandus also (Ration. Divin. 0ff. lib. 6, c. 10) relates that the pestilence which ravaged Rome, from the time of Pope Pelagius until Gregory the Great, and caused many thousand deaths, was sent by God in punishment of those, who, after the Lenten fast and the Easter communion, returned to their former wickedness. For they were to be visited with death who profaned the Eucharist, which is true life.

The meaning then is, "As the Father, who liveth by Himself, and is the Essence itself of life, hath sent Me into this world, and I have life from Him who begat Me, life, I say, both human, from a human soul, and of greater importance, Divine life, through partaking of the Godhead, with which My humanity is hypostatically united, and will be united for ever, so in like manner he who eateth the living Me, also from Me, ever abiding in Him as regards My Godhead, shall receive a perpetual life of grace and glory; and as regards his body, I will in due time raise it up into a blessed and eternal life." Christ here signifies that the life which is originally in the Father is communicated to us through the Son and the Eucharist, as by an organic means. So Leontius, Jansen, and others. But above the rest, S. Cyril, whom hear, "As I am made man by the will of the Father, who came forth from essential life, and as being man I live, and have filled My body with Life, no otherwise shall he who eateth My flesh live by Me. For I assumed mortal flesh; but because I exist as life essentially, dwelling in the flesh, I have made it wholly like unto My own life. For I indeed am not conquered by the death of the flesh, but as God I have overcome all death and destruction." And shortly afterwards, "As the Father hath sent Me, so that I am become man, yet I live by the Father, that is, I perfectly preserve the Father's nature: so he who shall receive Me by eating My flesh shall surely live, being made wholly like unto Me, who am able to give him life, because I am of the living Father." He adds a simile taken from red-hot iron. For as the fire communicates its heat to the red-hot iron, so does the living Christ impart His life unto us in the Eucharist. In admiration of this S. Augustine exclaims (lib. 7, Confess. c. 10), "0 eternal Truth, and true Charity, and sweet Eternity, I tremble with love and dread, as though I heard Thy voice from on high saying, 'I am the Bread of the strong: grow as thou shalt eat Me.'"

Observe here the gradation, by which life gradually descends to us from God as it were by stairs. The first step is, the Father communicating His own Divine Essence to the Son. The second, when the Son communicates the same life to the Humanity which He assumed by the participation of attributes. Third, when He inspires the life of grace and glory which He shares with It. The fourth, when He infuses not equal but like life into us in the Eucharist.

Lastly, Christ here signifies what I have spoken of in the preceding verse, that His Godhead which always abides in us, after the reception of the Eucharist, even after the species have been consumed, continually causes the life of grace to flow into us, and will after death raise us up again unto immortal life. This is what He means when He saith, I live by the Father, &c. He means, Because I receive Godhead, which is pure life from the Father, therefore he that eateth Me, even he shall live by Me. For My Godhead abiding in him, will continually breathe into his soul the breath of life. And his body shall after death be raised up by It to the beatific life. It is as the seminal virtue which lies hid in the heart of a grain of wheat, that seems dead through the winter, but in spring by the heat of the sun opening out its force, it, as it were, raises the grain of wheat itself from death, and causes it to germinate, and produce thirty and sixty fold.