...One crucified of the Trinity, and that he rightly professed blessed Mary to be truly and properly the Mother of God, and that there are two natures in Christ. We are most mercifully commanded to set forth the confession of thy faith, in concord with the definitions of the Council of Chalcedon — a confession which I have always approved, and which I have maintained against the contradictions of many. For since two heresies, refuted by that same council, are now seething — opposed indeed in their contention, yet alike in their detestableness, which assail the mystery of the divine Incarnation, I mean those of the Nestorians and of the Eutychians — what more healthful or more evident thing could be said against either heresy than that which thou thyself hast confessed: that one of the Trinity was crucified for us, whom the Apostle taught us to believe to be the great God, saying:
「For the grace of God our Saviour hath appeared to all men, instructing us that, denying ungodliness and worldly desires, we should live soberly and justly and piously in this world, looking for the blessed hope and the coming of the glory of the great God and our Saviour Jesus Christ」 (Titus 2:11-13). On account of which thou hast also said that the blessed Virgin Mary is truly and properly the Mother of God. For thou knowest not one as God the Word and another as Jesus Christ, whom in two natures thou hast pronounced to be one and the same, consubstantial with the Father according to the Godhead, and the same consubstantial with us according to the manhood; and concerning whom thou hast consequently said this also: 「For as He is perfect in Godhead, so the same is perfect in manhood.」
It is certain that thou hast brought forth all these things in accordance with the judgment of the Council of Chalcedon. For that the Lord Jesus Christ is one of the Trinity is evidently shown from the address of that same synod, which it made to the emperor Marcian. There, when it was defending the letter of the blessed Leo, prelate of the Roman Church, against the slanders of the heretics, after some words it speaks thus: 「It is easy to perceive that, when the ambiguity of the question arose, we are recognized to have conformed our confession to the interpretations of the Fathers, giving satisfaction that in nothing have we carried our mind to a meaning discordant with theirs, but that we use these as witnesses for the firmness of our faith. Thus we embrace the letter of Athanasius to Epictetus;
thus we everywhere set forth as our own the letter of Gregory to Cledonius. And what need is there to say more? For if they judge it worthy of blame that the doctrines of the Church should be declared through letters for each question, anyone could first of all mark out the most blessed Cyril himself, who expressed in his letters to the Easterns what he held; and he will likewise subject to this reproach the great Proclus, who sent to those same Easterns a volume to the Armenians for the agreement of the faith.」
「But to this blame there will also be joined the most wise John, bishop of Antioch, who, rejecting the slanders of the heretics and declaring the dogma of apostolic doctrine, sent the confession of the whole East, as it were from one mouth, to the most holy Proclus and to him who at that same time held the helm of the world.」 Now in this volume to the Armenians, which, as the said synod says, the great Proclus also sent to the Easterns for the agreement of the faith, he confessed thus (Roman edition, p. 128): 「For neither, in saying that the Son suffered, do we hold that He could suffer by reason of His Godhead, since the divine nature admits no passion whatsoever;
but confessing God the Word, one of the Trinity, to have been incarnate, we furnish matter for understanding to those who faithfully inquire why He deigned to be incarnate.」 Writing also to the blessed John of Antioch — to whom he directed those things also which he had written to the Armenians, for the preserving of the fellowship of the common faith, so that as all believed with one heart unto righteousness one and the same thing, so likewise there might be made by the mouth of all one and the same confession unto salvation — he speaks thus (Liberatus, ch. 10): 「But again, in saying that God, that is, Christ, is passible, we confess that He suffered not in that which He was, but in that which He became, that is, in His own flesh; and thus in our preaching we are in no way deceived,
since indeed we confess that one of the Trinity was crucified according to the flesh, and we in no wise blaspheme the Godhead as passible.」 And this sound doctrine of his the most wise John of Antioch, together with the Eastern council, approved by his letters; in which letters the said Council of Chalcedon testifies that he rejected the slanders of the heretics and declared the apostolic doctrine. Writing back to the same blessed Proclus, he said: 「The tome which was made to the Armenians by our most reverend son the deacon Theodosius — who is worthy to minister to thy directions, on account of the diligence beyond his years which is in him — we have both requested, and with all delight have made mention of him.
Now it caused us delight not by the beauty of its composition alone, nor by the multitude of arguments handled against both sides of the adversaries, so much as by the very carefulness and at the same time the piety of the sacred doctrines. Piety indeed, because, rightly confessing in those things which were said the word of truth, the royal road of the divine Scriptures, thou didst proceed, not presuming to preach anything of thine own authority without the testimonies of Scripture; and carefulness indeed, because together with the divine Scriptures thou didst also set forth the sayings of the Fathers, to prove what was said.」 Writing also to the blessed Cyril, the aforesaid John, together with the same synod of the East, declared that he had thus approved the tome itself to the Armenians:
「Since the most holy bishop Proclus,」 he says, 「has sent to us the tome which he wrote to the Armenians, truly and piously holding the right faith, and is seeking our consent, all things have been done by us, and in nothing have we done less.」 It has appeared, therefore, O religious emperor, that according to the judgment of that same great synod thou hast confessed one of the Trinity to have been crucified for us; seeing that this thy confession is contained in those letters to which it gave so great authority that by their example it judged that the letter of the blessed Leo should be defended (after the acts of the council). That also which thou saidst, that the blessed Mary is truly and properly the Mother of God, we find to be confirmed in the same address of the synod, where it was said:
「But the common enemy of our nature did not escape the unsleeping eye; rather, He at once showed our Fathers as luminaries to those whom the error of darkness had pervaded, that they might unlock for all the understanding of the faith, and might diligently proclaim the benefits of the Incarnation: how the sacrament of the dispensation was disposed from the beginning out of the womb; how also the Mother of God was called Virgin, on account of Him who deigned even to hallow her virginity after the birth, and, as became God, to seal her womb with integrity; how according to truth she was called Mother of God on account of the flesh which out of herself she ministered to the Lord of all.
」 Behold, this too has been shown, that the same holy synod taught that that Virgin was according to truth called the Mother of God, on account of the flesh which out of herself she ministered to the Lord of all. Nor does it matter whether she be called Mother of God according to truth, that is, truly, or truly and properly, as thou thyself hast confessed. For what John the Apostle calls the true Son of God, that same Paul calls His own (proper) Son. For thus he writes: We know that the Son of God is come, and hath given us understanding, that we may know what is true, and may be in His true Son Jesus Christ (1 John 5:20). But there, writing to the Romans, he says: If God be for us, who is against us? who also spared not His own proper Son, but delivered Him up for us all (Rom. 8:31-32).
Therefore it is nothing else that John calls our Lord Jesus Christ the true Son of God, than that Paul calls Him the proper Son of God. And so neither is it to be thought anything else that the holy Council of Chalcedon confessed the blessed Mary to be truly the Mother of God, than that thou thyself hast confessed her truly and properly the Mother of God. But if this is too little for anyone, and he still hesitates to call her truly and properly the Mother of God, let him await the fuller account of this very matter which we shall give below. Now that thou hast at the same time, according to the Council of Chalcedon, confessed the Lord Jesus Christ also in two natures, is shown by the definition of that same council:
in which it established that one and the same Christ, the only-begotten Son of God, is to be acknowledged in two natures, without confusion, without conversion, without division, and without separation; the difference of the natures being nowhere at all done away through the union, but rather the property of each nature being preserved. By all these things, therefore, the confession of thy faith is proved to accord with the definitions of the great council. On account of which we too have always congratulated it on its rightness, and have especially gloried over thee on its behalf. For what is to be praised first in a man? what is more excellently fitting in a prince, than the catholic faith, which is the foundation of all our good, and without which there is nothing good in us? For everything that is not of faith is sin.