But our opinion is in accordance with the Eucharist, and the Eucharist in turn establishes our opinion. For we offer to Him His own, announcing consistently the fellowship and union of the flesh and Spirit. For as the bread, which is produced from the earth, when it receives the invocation of God, is no longer common bread, but the Eucharist, consisting of two realities, earthly and heavenly; so also our bodies, when they receive the Eucharist, are no longer corruptible, having the hope of the resurrection to eternity. – Against Heresies 4:18:5 (189 A.D).

 

St. Irenaeus

Then, again, how can they say that the flesh, which is nourished with the body of the Lord and with His blood, goes to corruption, and does not partake of life? Let them, therefore, either alter their opinion, or cease from offering the things just mentioned. But our opinion is in accordance with the Eucharist, and the Eucharist in turn establishes our opinion. For we offer to Him His own, announcing consistently the fellowship and union of the flesh and Spirit. For as the bread, which is produced from the earth, when it receives the invocation of God, is no longer common bread, but the Eucharist, consisting of two realities, earthly and heavenly; so also our bodies, when they receive the Eucharist, are no longer corruptible, having the hope of the resurrection to eternity. – Against Heresies 4:18:5 (189 A.D).


If the Lord were from other than the Father, how could he rightly take bread, which is of the same creation as our own, and confess it to be his body and affirm that the mixture in the cup is his blood? – Against Heresies 4:33:2 (189 A.D).


He has declared the cup, a part of creation, to be his own blood, from which he causes our blood to flow; and the bread, a part of creation, he has established as his own body, from which he gives increase to our bodies. When, therefore, the mingled cup and the manufactured bread receives the Word of God, and the Eucharist of the blood and the body of Christ is made, from which things the substance of our flesh is increased and supported, how can they affirm that the flesh is incapable of receiving the gift of God, which is life eternal, which [flesh] is nourished from the body and blood of the Lord, and is a member of Him?— even as the blessed Paul declares in his Epistle to the Ephesians, that we are members of His body, of His flesh, and of His bones. [Ephesians 5:30] He does not speak these words of some spiritual and invisible man, for a spirit has not bones nor flesh; [Luke 24:39] but [he refers to] that dispensation [by which the Lord became] an actual man, consisting of flesh, and nerves, and bones—that [flesh] which is nourished by the cup which is His blood, and receives increase from the bread which is His body. And just as a cutting from the vine planted in the ground fructifies in its season, or as a grain of wheat falling into the earth and becoming decomposed, rises with manifold increase by the Spirit of God, who contains all things, and then, through the wisdom of God, serves for the use of men, and having received the Word of God, becomes the Eucharist, which is the body and blood of Christ; so also 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 granting them resurrection to the glory of God, even the Father, who freely gives to this mortal immortality, and to this corruptible incorruption, [1 Corinthians 15:53] because the strength of God is made perfect in weakness, [2 Corinthians 12:3]… – Against Heresies, 5:2:2-3 (189 A.D).