In this series of posts, we’re looking at the doctrine of the Incarnation as it was historically elaborated in the Christological controversies of the fourth through seventh centuries. We’ve already looked at St Cyril of Alexandria and the Nestorian controversy. St Cyril showed, against Nestorius, that Jesus Christ is one concrete subject from two natures, divinity and humanity, which he termed “hypostatic union.” As he frequently said, the difference between the natures is not confused by the union, but they cannot in any way be divided in reality. The divine Son of the Father and the human son of Mary are one and the same, whose life, death, and resurrection are what saves us and unites us to God.
This certainly wasn’t the end of controversy, however. Shortly after Cyril’s death, in 448, a monk and archimandrite named Eutyches who had been a member of Cyril’s party against Nestorius was charged with heresy and brought before the synod of Constantinople. The bishops present there – led by St Flavian, bishop of Constantinople – concluded from Cyril’s Second Letter to Nestorius and the Formula of Reunion that it was necessary to confess Christ as “from two natures” and “in two natures” after the incarnation. Eutyches, on the other hand, said (when pressed) that “I confess that our Lord was from two natures before the union, but after the union, one nature”; and refused to think “that the body of our Lord and God was consubstantial with us.” [12] His condemnation for holding these views sparked another period of strife for the Church.
“He who is true God is also true human”
In response to this judgment, Eutyches appealed to the bishops of Rome, Alexandria, Jerusalem and Thessalonica to vindicate him. This appeal was heard by the emperor St Theodosius II through the influence of Eutyches’ godson, the powerful eunuch Chrysaphius, at the emperor’s court. Theodosius II therefore called an ecumenical council at Ephesus to be held later in 449. The council of Ephesus (II) was to be chaired by Dioscorus, bishop of Alexandria, who had been a hardliner within Cyril’s party and saw this as an opportunity to defeat a new Nestorius (i.e., St Flavian) and get rid of the pesky Antiochene party with whom St Cyril had made peace in 433. Although the proceedings of Ephesus II were hotly contested afterward, Dioscorus was later – as Cyril had been at Ephesus I – accused of using force and intimidation at the council. Flavian was deposed and died under mysterious circumstances, while Domnus II of Antioch, Theodoret of Cyrrhus, Ibas of Edessa, and others were also removed.
Prior to Ephesus II, both Eutyches and Flavian had written to St Leo bishop of Rome to try and get him on their side. Leo concluded that Eutyches had fallen ignorantly into heresy in his old age and wrote a letter back to Flavian, now known as the Tome of Leo, to help teach Eutyches and bring him back to the orthodox faith. Dioscorus prevented this letter from being read at Ephesus II, and the deacon St Hilary, the Roman representative at the council, formally objected to the council and escaped with difficulty. [13] St Leo’s Tome was later read and proclaimed to be orthodox at the council of Chalcedon (451) which overturned Ephesus II. Thus, it’s worth looking at this text to discover the orthodox Christology that was presented at Chalcedon.
The Tome begins with a condensed creed:
The whole multitude of the faithful... believes in God the Father Almighty, and in Christ Jesus his only-begotten Son our Lord, born from the Holy Spirit and Mary the Virgin – three declarations by which the machinations of virtually all the heretics are defeated. (2a) [14]
St Leo seeks to show that this creed implies the two natures of Christ. Because God is the Father, “the Son is also revealed as coeternal with him, in no respect differing from the Father, since he is God from God” (2b). It is the same subject, “the eternal only-begotten of the eternal Father,” who “was born from the Holy Spirit and Mary the Virgin; this birth in time neither subtracted anything from his divine and eternal birth nor added anything to it” (2b). Leo continues into soteriology: we could not defeat sin and death unless “he whom neither sin could defile nor death detain... [had] assumed our nature and made it his own” (2b).
If the Creed isn’t enough for Eutyches, then the Scriptures also show that Jesus Christ was truly born as a human (2c). Matthew refers to “the generation of Jesus Christ, the son of David, the son of Abraham” (1:1). Paul says that “his Son... came to be from the seed of David according to the flesh” (Rom 1:1-3). Abraham was promised, “In your seed all the nations will be blessed” (Gen 22:18), and that seed “is Christ” (Gal 3:16). Isaiah prophesied that “the Virgin will conceive in her womb and will bear a son, and they will call his name... God with us” (7:14), and “A child has been born for us... and they will call his name Angel of great counsel, mighty God” (9:6). This refutes Eutyches’ view that “the Word became flesh in such a way that Christ born from the Virgin possessed human form but did not possess the truth of his mother’s body” (2c). [15]
Perhaps the reason Eutyches thinks “that Christ the Lord is not of our nature” is because of Luke 1:35, which says that the Holy Spirit would come upon Mary, so that the one who is born “will be called the Son of God.” But the uniqueness of Christ’s birth has no bearing on “the distinctive property [proprietas] of the race” (2d). “For the Holy Spirit gave the Virgin fruitfulness, but the truth of the body was taken from [her] body, and when ‘Wisdom built itself a house’ [Prov 9:1], ‘the Word became flesh and dwelt among us’ [John 1:14], that is, in this body which he took from man and which he animated with the spirit of a rational life” (2d).
Having proven that Jesus Christ is both truly divine and truly human, Leo describes the true unity of these two natures:
With, therefore, the distinctive character of each nature being preserved and coming together into one person, lowliness was assumed by divinity, impotence by power, mortality by immortality; and for the payment of the debt owed by our nature the divine nature was united to the passible nature, so that – this fitting our cure – one and the same, being ‘the mediator between God and men, the man Christ Jesus’ [1 Tim 2:6], would be able to die in respect of the one and would not be able to expire in respect of the other. Therefore in the pure and perfect nature of true man true God was born, complete in what is his own and complete in what is ours. (3a)
His statement about “each nature... coming together into one person [unum personam]” is unfortunately ambiguous, since the Latin persona can refer both to a person’s external manifestation (Greek prosōpon) and their concrete subjectivity (Greek hypostasis). Nestorius confessed that Christ is one prosōpon, but saw both a divine and a human hypostasis. This ambiguity may contribute to the later non-Chalcedonian claim that the Tome is Nestorian. However, since St Leo says that Christ is “one and the same,” it’s clear that he sees Christ as a single concrete subject.
The “ours” in which Christ is complete is the nature that God created in the beginning and restored, not the sin which the devil added (3b). He thus “assumed the form of a servant without any defilement of sin, augmenting the human without lessening the divine” (3b). In other words, “the one who while remaining in the form of God created man, himself in the form of a servant became man”; neither nature or form is diminished by the presence of the other (3b). Because humanity was deceived by the devil and stripped of immortality, and God’s justice required the loss of our original honor, we needed “the dispensation of the ineffable mystery” so that God’s goodness would be revealed toward us and we could be restored (3c).
The next section is the central part of the letter in which St Leo describes the “ineffable mystery,” that is, the Incarnation. It’s worth quoting in full:
Therefore the Son of God enters this lowly state of the world, descending from his heavenly throne without being separated from the glory of the Father, born by a new order and a new birth – by a new order because, although invisible in what is his own, he became visible at our level and, although incomprehensible, he willed to be comprehended and, while remaining eternal, he began to be in time and, although master of the universe, he received a servile form, after veiling the greatness of his own Godhead; the impassible God did not disdain being a passible man, nor the immortal one to submit to the laws of death. And he was born by a new birth, since inviolate virginity, without experiencing desire, provided the material of the flesh. There was taken from the mother of the Lord nature but not sin; nor, because in the Lord Jesus Christ born from the womb of the Virgin the generation is a marvellous one, is his nature for this reason unlike ours. For the one who is true God is himself also true man.
And there is no deceit in this union, in that both are with each other, both the lowliness of the man and the greatness of the Godhead; for just as God does not undergo change through compassion, so the man is not consumed by the greatness of divine dignity. For each form performs what is proper to it in communion with the other, the Word achieving what is the Word’s, while the body accomplishes what is the body’s; the one shines with miracles, while the other has succumbed to outrages. Just as the Word is inseparable from equality with the glory of the Father, so the body has not abandoned the nature of our race. For one and the same is truly Son of God and truly son of man, God in that ‘in the beginning was the Word, and the Word was with God, and the Word was God’ [John 1:1], man in that ‘the Word became flesh and dwelt among us’ [John 1:14], God in that ‘through him all things came into being, and without him not one thing came into being’ [John 1:3], man in that ‘he came into being from a woman, and came into being under the law’ [Gal 4:4].
The generation of the incarnation is a display of human nature, while the childbearing of the Virgin provides an indication of divine power; and the infancy of the child is recognized through the meanness of the swaddling clothes, while the greatness of his majesty is shown by the voices of the angels. He whom Herod impiously plots to kill is like human beings newly born, but it is the master of the universe whom the Magi rejoice to worship with supplication. And when he came to the baptism of his forerunner John, in order that he should not escape notice because his Godhead was hidden by the veil of flesh, the voice of the Father resounding from heaven said, ‘This is my beloved Son in whom I am well pleased’ [Matt 3:17]. Accordingly he who as man is tempted by the devil’s craftiness is served as God by the rank of the angels. For to hunger and thirst, to be weary and to sleep are confessedly human, but to satisfy five thousand men with five loaves and to give the Samaritan woman living water, which, when she drew it, made her never thirst again, to walk on the surface of the sea without one’s feet being wetted, and to still the surging of the waves by rebuking the swell is without doubt of God.
As therefore, to pass over most of the instances, it is not of the same nature to weep for a dead friend from a disposition of pity and, when the mound of a burial already four days old was demolished, to raise him up to new life by a command of the voice, or to be hung on the cross and to shake all the elements, changed from night to day, or to be pierced with the nails and to open the gates of paradise to the faith of the thief, so also it is not of the same nature to say, ‘I and the Father are one’ [John 10:30], and to say, ‘My father is greater than I’ [John 14:28]. For although indeed in the Lord Jesus Christ there is one person of God and man, nevertheless that because of which the outrage is common in both is one thing and that because of which the glory is common is another. For he has from us the humanity that is less than the Father, and he has from the Father the Godhead that is equal with the Father. (4)
This passage of Leo’s Tome was controversial, both at the council of Chalcedon and afterward, as some saw the language of each nature “performing what is proper to it” (even though “in communion with the other”) as Nestorian. However, throughout the entire section, it’s one “he” who’s the subject of both divine and human activities. St Leo’s point is that we can – and indeed must – distinguish what is divine and what is human in Christ, even though these aren’t separable in reality. Each of the couplets shows that Christ’s human activities (e.g., being conceived) are performed divinely (e.g., by a virgin), and vice versa. Leo’s argument here, and the Tome as a whole, is summed up by his statement that “the one who is true God is also himself true man... one and the same is truly Son of God and truly son of man” (4ab).
Because, then, of this union of person that needs to be conceived in each nature we also acknowledge that the Son of man came down from heaven, when the Son of God assumed the body from the Virgin from whom he was born, and again the Son of God is said to have been crucified and buried, when he endured these things not in the Godhead itself in which he is only-begotten, coeternal and consubstantial with the Father, but in the weakness of his human nature. Whence it is that in the creed itself we all acknowledge the only-begotten Son of God crucified and buried, according to that apostolic saying, ‘For if they had known, they would not have crucified the Lord of glory’ [1 Cor 2:8]. (5a)
In other words, the union of divinity and humanity in one person means that the attributes of both belong to one subject, so we can say that the Son of Man came down from heaven and the same Son of God was born, crucified, and buried. When Jesus asked his disciples, “Who do you say that I am?,” and Peter replied, “You are the Christ, the Son of the living God,” this shows that it’s necessary to confess one person as both Son of God and Christ (i.e., an anointed human; 5b). Likewise, when the Crucified one rose again, he appeared to his disciples by entering a room with a closed door, bestowing the Holy Spirit, and revealing divine secrets, while also showing the bodily wounds of his suffering. This was so “that we might learn in this way that the Word is not the same as the flesh, but might acknowledge that both the Word and the flesh are the one Son of God” (5c).
Therefore, Eutyches is wrong when he “fails to acknowledge our nature in the only-begotten of God,” and he thereby denies that “Jesus Christ has come in the flesh” and “divides” him (1 John 4:2-3) from his humanity (5d). If he denies that Jesus has a truly human body, then he must also deny Jesus’ true suffering and true blood, despite Sts Peter and John (1 Pet 1:18-19; 1 John 1:7; 5:4-8) who say that we are saved by the blood of Jesus (5e). The faith of the Church is that “neither the humanity without the true divinity, nor the divinity without the true humanity, may be believed [to exist]” (5e). Eutyches’ statement, “I profess that our Lord was from two natures before the union, but after the union I profess one nature,” is therefore utterly reprehensible, and he should be taught and given the opportunity to repent (6).
“Leo and Cyril taught the same!”
At the council of Chalcedon, the creeds of Nicaea (325) and Constantinople (381) along with the letters of St Cyril to Nestorius (Second Letter) and John of Antioch (Letter 39, with the Formula of Reunion) were read, all of which were acclaimed by the bishops (Acts of Chalcedon II.9-20). The Tome of Leo, which was prevented from being read at Ephesus II, was then read (II.21-22). According to the acts of the council, then “the most devout bishops exclaimed [among other things]... ‘Leo and Cyril taught the same’” (II.23). However, many hardline Cyrillians, both at the time and later, saw the Tome as Nestorian. So did St Leo and St Cyril really teach the same doctrine?
Chalcedon wasn’t merely intended to be the victory of Leonine Christology (except, perhaps, for the emperor St Marcian whose main purpose was to reunite with the West). The council was really about who the genuine theological successors of Cyril were: the Alexandrian hardliners, like Eutyches and Dioscorus, who rejected union with the Antiochenes, or the more moderate Cyrillians who accepted “two natures” (when interpreted correctly)? In fact, the bishops were so loyal to St Cyril that even Theodoret of Cyrrhus, who had been one of Cyril’s chief opponents, had to quote him to defend the Tome (II.26). The Illyrian bishops, who were sympathetic to the hardline position, were given several days to examine the Tome and see if it agreed with Cyril (II.29ff). [16] Therefore, even if the Tome can be interpreted in a Nestorian way, the council was determined to accept it only as Cyrillian.
How congruent really was St Leo’s Christology with St Cyril’s? On Cyril’s most important point – that the incarnate Word, Jesus Christ, is one single subject – Leo was in perfect agreement. The Tome is clear that it is “the same eternal only-begotten of the eternal Father” who “was born of the Holy Spirit and the Virgin Mary” (2b). It is “one and the same... ‘the man Christ Jesus’” to whom belongs contrary attributes, who is “able to die in respect of the [humanity] and not able to expire in respect of the [divinity]” (3a); and “one and the same is truly Son of God and truly son of man” (4b). The communication of attributes, which Cyril saw as the necessary result of Christ’s single subjectivity (and which Nestorius could not “strictly” support), is explicitly stated by Leo (5a).
The controversial aspects of the Tome are the sections which stress Christ’s duality. The Illyrian and Palestinian bishops at Chalcedon objected to a few passages: “Christ Jesus would be able to die in respect of the [humanity] and not able to expire in respect of the [divinity]” (3a); “each form performs what is proper to it in association with the other, the Word achieving what is the Word’s, while the body accomplishes what is the body’s” (4b); “he has from us the humanity that is less than the Father, and he has from the Father the Godhead that is equal with the Father” (4d). In response, Aetius of Constantinople and Theodoret of Cyrrhus cited similar statements from St Cyril:
...since his own body ‘tasted death by the grace of God on behalf of all’ [Heb 2:9], as Paul says, then he himself is said to have suffered death for our sake. This does not mean he underwent the experience of death in terms of his nature for it would be madness to say or think such a thing; rather, as I have said, it means that his flesh tasted death. (Second Letter to Nestorius 5)
Some of the sayings are particularly fitting to God, some again are particularly fitting to man, while others occupy a middle position, revealing the Son of God as God and man simultaneously and at the same time. (Letter 40.16)
He became man without shedding what was his own, for he remained what he was; he is certainly conceived as one dwelling in another, that is, the divine nature in what is human. (Scholia on the Incarnation 25)
St Leo’s statement about Christ’s humanity and divinity performing different activities could indeed be interpreted in a Nestorian way. However, he goes on to say that these natures and activities belong to “one and the same,” and throughout this section it’s one “he” who is the subject of each activity. In Leo’s letter 124 to some non-Chalcedonian monks in Palestine (which came to be known as his Second Tome), he clarifies that “the person of the Word and the flesh is one, and both have their actions in common”; what we distinguish are “what it is that the flesh without the Word, or the Word without the flesh, does not do” (124.5). In other words, the incarnate Christ does nothing apart from both divinity and humanity, but we can discern (not separate in reality) the activities which are grounded in either the divine nature or the human nature.
It’s clear that Cyril preferred not to speak of “two natures” since he saw this language as tending to divide Christ. At the same time, he accepted that this had an orthodox interpretation, since he accepted “two natures” in the Formula of Reunion and defended it against hardliners in his own party. In his letters to Acacius and Succensus, he emphasized that Christ’s union is “from two natures,” which are not divided “after the union” (44.6). Of course, this isn’t meant as a temporal sequence (i.e., that there were two separate realities which became one reality), but that we can mentally abstract divinity and humanity out of the one Lord Jesus Christ without dividing him: “before” and “after” refer to two different ontological levels rather than two different times. Thus in his writings, both before and after the controversy, St Cyril frequently distinguishes between Christ’s activities and sayings “as God” and “as man” while attributing them to one and the same subject. [17]
This terminology (“from two natures,” not “after the union”) became a flashpoint for later controversy which led to Chalcedon. The Alexandrian hardliners saw the confession of St Flavian and other bishops, against Eutyches, that Christ is from and in two natures after the union as an admission that they divided Christ into two separate realities. Hence, Dioscorus insisted at Chalcedon, “I accept ‘from two’; I do not accept ‘two’” (Acts of Chalcedon I.332). In contrast, St Flavian and the others interpreted Eutyches’ refusal to accept Christ as in two natures after the union to mean that he denied any difference between humanity and divinity in Christ at all. St Leo even took Eutyches’ confession that “our Lord was from two natures before the union, but after the union, one nature” as referring to a temporal sequence, viewing it as a strange sort of adoptionism in which God and a man, existing separately, became one thing (Tome 6a).
In summary, despite subtle differences in terminology, the teaching of St Leo and St Cyril was actually the same. This agreement in meaning between (orthodox) Alexandrians and (orthodox) Antiochenes was what Cyril himself recognized when he agreed to the Formula of Reunion, and the hardliners in his own party failed to see, which led to their eventual downfall at Chalcedon. The Chalcedonian Definition sums up this agreement well:
Following, therefore, the holy fathers, we all in harmony teach confession of one and the same Son our Lord Jesus Christ, the same perfect in Godhead and the same perfect in manhood, truly God and the same truly man, of a rational soul and body, consubstantial with the Father in respect of the Godhead, and the same consubstantial with us in respect of the manhood, like us in all things apart from sin, begotten from the Father before the ages in respect of the Godhead, and the same in the last days for us and for our salvation from the Virgin Mary the Theotokos in respect of the manhood, one and the same Christ, Son, Lord, Only-begotten, acknowledged in two natures without confusion, change, division, or separation (the difference of the natures being in no way destroyed by the union, but rather the distinctive character of each nature being preserved and coming together into one person and one hypostasis), not parted or divided into two persons, but one and the same Son, Only-begotten, God, Word, Lord, Jesus Christ, even as the prophets from of old and Jesus Christ himself taught us about him and the symbol of the fathers has handed down to us. (Acts of Chalcedon V.34)
This definition uses terminology from both Alexandria (“one and the same... not parted or divided”) and Antioch (“consubstantial with the Father... consubstantial with us... in two natures”) to summarize a basically Cyrillian Christology. [18] There is one single subject, the Lord Jesus Christ, who is both truly God the Word and truly a human being, truly born from the Father and truly born from Mary, one and the same Son of God and son of man.
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[12] The deposition of Eutyches is recorded in the Acts of Chalcedon I.458-552, with interpolations from Ephesus II and Chalcedon.
St Cyril also never referred explicitly to two natures after the Incarnation, although he did speak of Christ’s divinity and his humanity as natures which were not confused by the union. Eutyches’ statement about two natures before the union and one nature afterward is more or less what Cyril said in his letters to Succensus. Eutyches’ mistake was to speak of “one nature” unqualifiedly rather than adding “incarnate” (as Cyril did), which the bishop Basil of Seleucia pointed out during the proceedings, but this is understandable since he confessed being unfamiliar with using the language of “natures” to refer to God. Eutyches did say that Christ is “perfect human” (teleios anthropos), so his denial that Christ’s body is consubstantial with us – which certainly went much further than St Cyril – is difficult to explain.
It’s unclear whether Eutyches actually held the heretical view attributed to him (that Christ has one divine nature and not a human nature). He was theologically untrained and his views were somewhat muddled. It looks like he was one of the Alexandrian hardliners who refused to accept the Formula of Reunion and saw it as a betrayal, which would explain why he was opposed to the language of “two natures” and double consubstantiality. His condemnation was ultimately because he refused to accept this language and to anathematize other Alexandrian hardliners, which threatened the reunion.
[13] Hilary apparently escaped by hiding in a chapel of St John, and brought letters from St Flavian and Eusebius of Dorylaeum (who had been Eutyches’ accusers) to the pope Leo which prompted him to refer to Ephesus II as a latrocinium (“robber council”). Hilary’s escape is commemorated by an inscription in the baptistry of the Lateran Basilica from after he became bishop of Rome, which reads, “To his liberator, blessed John the Evangelist, Hilary the bishop, slave of Christ.”
[14] Translation from Richard Price and Michael Gaddis, The Acts of the Council of Chalcedon (Liverpool University Press, 2005), 2:14-24.
[15] This view is taken from the acts of the home synod of Constantinople in 448, in which the bishop Eusebius of Dorylaeum claimed that, in conversation with him, Eutyches “acknowledged as perfect God and perfect man the one who was born from the Virgin Mary but [he] does not have flesh consubstantial with us” (Acts of Chalcedon I.359). During his own deposition, Eutyches said, “Till today I have not said that the body of our Lord and God is consubstantial with us, but I acknowledge that the Holy Virgin is consubstantial with us, and that our God was enfleshed from her” (I.516).
[16] Richard Price and Michael Gaddis, The Acts of the Council of Chalcedon, 1:65-75.
[17] Daniel A. Keating, “The Christology of Cyril of Alexandria,” Religions 15 (2024): 688.
[18] The Definition even echoes language used by Dioscorus himself. In the first session of the council, he said, “We speak of neither confusion nor division nor change. Anathema to whoever speaks of confusion or change or mixture” (Acts of Chalcedon I.263); and the Definition refers to “two natures without confusion, change, division, or separation” (V.34).
