In this post in my series “God and Man at Yale Divinity,” I share my paper on the Council of Chalcedon. It was my final paper for the History of Early Christianity class that I took during my first semester at Yale Divinity School. This content uses referral links.
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What follows below is, with some minor modifications, a copy of my paper on the Council of Chalcedon. This was my final paper for the History of Early Christianity class that I took my first semester at Yale.
I have always been fascinated by Ecumenical Councils, and, as I began to study this one, I became fascinated by all the politics that were at work as this theological dispute played out. Unfortunately, the page limit prevented me from fleshing this out as much I would have liked, so this is a relatively brief survey of the influence of the Council of Chalcedon.
I hope that this paper is of value to you. I have also included a pdf copy of my paper below for those who prefer that format. The full bibliography is only included in the pdf copy.
The Council of Chalcedon
Most would not recognize the name Gavrilo Princip. Yet, on June 28, 1914, this obscure man, by assassinating the heir to the Austro-Hungarian throne, set in motion a series of events that have impacted nearly every aspect of the modern era.
In the same way, the Council of Chalcedon of 451 maintains relative obscurity, but its effects have rippled throughout history. Like Princip, Chalcedon changed the map, altering spheres of influence and breaking down old power bases while creating others.
Indeed, this controversial, widely panned, and frequently ignored council inadvertently concentrated ecclesiastical power almost exclusively into the hands of the bishops of Rome and Constantinople, setting in motion a series of unanticipated events that would change Christendom forever.
Background to the Council
Two main factors led to the Council of Chalcedon. The first was the theological controversy over how Christ’s divine and human natures coexist. The second was the political, that is, the power-jockeying within the Church between the great sees of Rome, Constantinople, Alexandria, Antioch, and Jerusalem.
This paper will evaluate the record of the Council’s proceedings and the correspondence of its leading power players to explore the political considerations driving the Council. While it would be overly cynical to conclude the debates surrounding Chalcedon were solely matters of power struggles and political expediency, space simply does not allow full exploration of the relevant complex theological issues. 
The Council of Ephesus and Its Aftermath
In 431, the Byzantine Emperor, Theodosius II, called a general council of bishops to address a controversy that had arisen between Nestorius, the Bishop of Constantinople, and Cyril, the Bishop of Alexandria, over the nature of Christ. In essence, Nestorius, representing the Antiochene school of thought, heavily emphasized the distinction between Christ’s divine and human natures, while Cyril insisted that the “unified person Jesus Christ could not…be separated into divine and human components.”
On June 22, 431, Cyril, serving as president of the Council by virtue of his position as Bishop of Alexandria and as the representative of Pope Celestine, commenced the proceedings at Ephesus. The Council, in short order, condemned the teachings of Nestorius.
This did not, however, settle the matter. Two decades of unrest between the Antiochene and Alexandrian schools followed, and, in fact, churches beyond the eastern boundaries of the Empire broke off communion with the Imperial Church after the Council.
It is important to remember that theological disputes affected not just the ecclesiastical hierarchy but the local populace as well. Westerners in a post-Westphalian world can easily overlook the feelings of nationalistic resentment imperials systems can inspire. These imperial subjects were “living in days when strong patriotic feelings could be expressed only through the medium of theological controversy.”
The Antiochene and Alexandrian schools represented not just different theological positions but different nationalities within an ethnically diverse empire. This reality, therefore, makes sense of imperial involvement in theological disputes, something that may seem bizarre to modern Westerners operating with an assumed separation of religion and politics. At that time, however, religion infused every aspect of public life.
In a pre-Enlightenment world, religious uniformity was, therefore, a way to maintain peace within an Empire encompassing a large variety of nationalities.
In 433, Emperor Theodosius II, with the cooperation of Cyril and John, the Bishop of Antioch, achieved a tenuous peace between the factions. Nonetheless, the “fundamental theological divisions remained unresolved.”
When Eutyches, an archimandrite at Constantinople, refused to recognize that Christ possessed two natures, the Antiochene school saw this as a denial of Christ’s humanity, confirming their worst fears about the Ephesian teaching. A synod at Constantinople deposed Eutyches in 449, but he appealed to the bishops of Rome, Alexandria, Jerusalem, and Thessalonica.
Dioscorus, Cyril’s less moderate successor and “resolute anti-Nestorian,” saw this as an opportunity to hold another ecumenical council, through which he could impose Alexandrian Christology throughout the Empire while simultaneously increasing the prestige of his see.
In an effort to stave off a general council, Flavian, the Bishop of Constantinople, asked Pope Leo to endorse the synod’s judgment. Leo responded with his widely-celebrated Tome, which he intended to be the “definitive pronouncement on the faith.” In it, Leo condemned Eutyches and strongly affirmed the two-natured Christology. Nonetheless, the Emperor, at Dioscorus’ behest, called another general council to resolve the issue.
Struggle Among the Great Sees
Tensions between the great sees of Alexandria, Constantinople, Antioch, Jerusalem, and Rome underpinned these Christological controversies.
Nestorius had been brought up in the “Antiochene way of belief,” and Cyril, as the occupant of the throne of St. Mark, had used his dispute with Nestorius to undercut “the upstart see of Constantinople.”
The bishops of Alexandria had seen the First Council of Constantinople’s elevation of the Imperial See to second after Rome in 381—a position their see previously occupied—as a blow to their prestige. Opposing Nestorius, however, pitted Alexandria against both Constantinople and Antioch.
The see of Antioch boasted association not with the “interpreter of St Peter,” that is Mark, but with Peter himself. It lacked, however, the wealth of Alexandria and consequently wielded less authority. The rivalry between Antioch and Alexandria was such that both Cyril and Dioscorus supported efforts to elevate the Jerusalem see to patriarchate status, a promotion that could only come at Antioch’s expense.
Into all of this, Rome interjected itself. The papacy enjoyed tremendous prestige as a result of Rome’s apostolic foundations—both Peter and Paul were martyred there—and its place as the historical seat of the Empire. On this basis, the bishops of Rome “claimed a primacy over the church that derived from Christ’s commission to Peter.” Leo’s Tome, however, marked a largely unprecedented interference of the Latin West into Greek theological disputes.
Dioscorus, for his part, cared little for Leo’s Tome and had little concern for the “dignity of Rome.” He planned to make it clear that Alexandria—not Antioch, not Constantinople, and certainly not Rome—“was supreme in Eastern ecclesiastical affairs.”
Ephesus II and Chalcedon
In 449, nearly one hundred thirty bishops gathered for the Second Council of Ephesus in what would become a remarkable triumph for the Alexandrian cause. Running roughshod over his opposition, Dioscorus ignored both the papal request to read the Tome aloud and Flavian’s request to allow Eusebius—Eutyches’ accuser at the previous home synod—to speak.
Soldiers and “club-wielding monks” then secured acquiescence to Dioscorus’ “one nature after the union,” formula and his decree of deposition against Flavian and Eusebius. Flavian and Eusebius were treated as prisoners, and Flavian died as a result of his rough handling. Hilary, a papal legate and future pope himself, barely managed to escape.
Dioscorus’ victory at what Pope Leo would brand the “Robber-Synod,” however, would be short-lived.
Given the blow papal prestige had suffered at Ephesus II, one wonders what the papacy would look like today were it not for this one accident of history: on July 28, 450, Emperor Theodosius II fell from his horse and died.
Marcian, Theodosius’ successor, would not accept Alexandrian supremacy. He reached out to Pope Leo, who demanded the affirmation of his Tome as a condition of renewed relations. Both Marcian and Anatolius, the new Bishop of Constantinople, obliged and encouraged other bishops to do the same.
The Emperor then ordered another council in 451. Dioscorus, convinced Leo was propagating Nestorian thought, excommunicated the Pope on the way to Chalcedon. The Council would now be a clear showdown between Alexandria and Rome.
Records of the proceedings show the battle lines to have played out as anticipated. Leo’s Tome finally received its hearing. At the reading’s conclusion, the bishops exclaimed, “This is the faith of the fathers. This is the faith of the apostles…Peter has uttered this through Leo.”
(It must be recognized, however, that this reflects the official record of proceedings, and both imperial and ecclesiastical authorities had an incentive to downplay the level of dissent among the Council’s participants.)
Dioscorus was subsequently deposed, and the Council’s Definition of Faith conformed itself to Leo’s Tome. For what more could the Pope have hoped?
In the years that followed, “[t]heological division, political rivalry and sectarian violence combined to produce what ultimately became Chalcedonian and miaphysite churches, a split that persists to this day.”
Chalcedon did, however, bring three significant achievements: the separation of the Alexandrian-miaphysite Church from the Imperial Church, the increase of papal prestige, and the strengthening of the Constantinopolitan see.
Separation of the Miaphysites 
After Chalcedon, Emperor Marcian installed a new bishop of Alexandria by military force. Resistance to Chalcedon was fierce in Egypt, where nationalist resentment simmered, and the Emperor’s bishop was assassinated after Marcian’s death in 457.
Various efforts were made over the succeeding years to bring about reconciliation but to no avail. Two ecclesiastical networks consequently emerged in Egypt, one Chalcedonian and one not. Consequently, the Bishop of Alexandria, once considered the second see after Rome, ceased to be a power-player with which Constantinople and Rome had to contend. This allowed Constantinople to consolidate its power in the East.
Increase of Papal Prestige
The Council was an almost unmitigated success for Leo. The Emperor himself had acknowledged the Council to be held on the Pope’s authority as the one “possessing primacy in the episcopate of the divine faith.”
In addition, the Pope had principally provided the Definition of Faith through his Tome. Indeed, “[i]t would be a mistake to interpret the Definition as a synthesis between Alexandria and Rome. The Council solemnly approved the Tome of Leo, and it was a result of Roman insistence that the Definition contains an unambiguous statement of two natures in Christ.”
As ecumenical councils were held in the East, the various popes, not condescending to appear at imperial summons, sent representatives “who attempted to create an impression of being in charge.” This insistence of the papal legates that their role “was not to deliberate along with the assembled bishops but rather to inform them of the pope’s judgment,” was more or less true at Chalcedon.
“It was the first opportunity the Roman see had had of extending its prestige and authority in the East through any paramount or even prominent part in a general council, and everything conspired…to make it a very great opportunity.” Indeed, Rome had faced down the powerful Alexandrian see—the see of Athanasius and Cyril—and had won.
Strengthening of Constantinople
The Pope’s will failed to prevail on one point only: the twenty-eighth canon, which affirmed Constantinople as the new Rome with equal privileges to the old Rome and second only after her in ecclesiastical affairs. Again, political interests were at play. Marcian was determined that the Church in the East would be governed from the Imperial Capital, not from Alexandria and not from Rome.
Consequently, even after Chalcedon had made his Tome the de facto definition of the Christian faith, it took over a year of negotiations before Leo was willing to provide the written approval of the Council that the Emperor requested. Even then, Leo maintained his objection to the twenty-eighth canon.
The canon exalted Constantinople at the expense of Antioch and Alexandria. Rome, therefore, vanquished one major rival only to be left with an even stronger one. Alexandria had had wealth and a historical pedigree, but now Constantinople had the endorsement of two ecumenical councils and the backing of the full strength and power of Empire.
In addition, Antioch ceded some of its jurisdiction to Jerusalem, thus weakening it further and leaving Constantinople unchallenged for Eastern supremacy.
Even if the theological clash underpinning Chalcedon was based merely on “mutual misunderstanding rather than any significant doctrinal differences at play,” its ramifications were very real and long-lasting. Chalcedon kicked off an ongoing dispute that would take on greater complexity over the centuries.
Alexandria separated from the Church. Jerusalem—never a real power player—was elevated, further weakening an already frail Antiochene see. Constantinople and Rome enjoyed a significant increase in prestige, the former by fiat and imperial influence, the latter by theological victory consistent with its already strong historic claims to authority.
Chalcedon, therefore, left only two great patriarchates to fight for supremacy in the Church.
So, the stage was set for the great rivalry between Rome and Constantinople that would eventually culminate with the Great Schism of 1054. Then, separated from the counterbalancing influence of the East, the modern papacy was, if not an inevitability, a natural result. The most natural progeny of Chalcedon, therefore, is Vatican I.
 Two world wars, the Cold War, the current Mid-East crisis, decolonization, and the rise of the United States as a global superpower all burst, in one sense or another, from the barrel of Princip’s gun.
 Indeed, after the Council, “the Greek world at least went on in its task of thinking about the problem as though nothing had been said at Chalcedon.” William P. Du Bose, The Ecumenical Councils (New York: The Christian Literature Company, 1896), 259-60.
 It is essential to recognize the philosophical presuppositions that underpinned the debate at Chalcedon and affected the intensity with which various groups would later resist the Council’s decision. The bishops’ philosophical presuppositions about the divine, particularly as they relate to divine immutability and impassibility, lay at the heart of much of the debate. Divine changelessness was a concern for both sides—the sacrosanct nature of divine immutability drove, in particular, the Nestorian and Antiochene stress on the distinction between Christ’s natures—and would remain a concern for theologians thereafter. See Richard Price and Michael Gaddis, “General Introduction,” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 1:60; “Session II, 10 October 451,” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 2:18; Anselm, Proslogium; Monologium; An Appendix in Behalf of the Fool by Gaunilon; and Cur Deus Homo, trans. Sidney Norton Deane (Chicago: The Open Court Publishing Company, 1903), 13-14; Brian Bantum, Redeeming Mulatto: A Theology of Race and Christian Hybridity (Waco: Baylor University Press, 2010), 103. The lack of such presuppositions would have prevented Leo’s need to divide Christ’s actions between his divine and human natures, which prompted such fierce resistance after the Council. “Session II,” 2:19; Irineu Ion Popa, “Christology of Chalcedon, after the Council of Chalcedon,” Studia Teologiczno-Historyczne Śląska Opolskiego 1 (2016): 15.
 The question was not whether Christ was both God and man—everyone affirmed that—but how he was both. Du Bose, 259-60.
 Indeed, each side was “firmly persuaded that it was fighting for the preservation of the truth of the Gospel.” R. V. Sellers, The Council of Chalcedon: A Historical and Doctrinal Survey (London: S.P.C.K., 1953), 7; see also Bantum, 103.
 Du Bose, 222.
 Dale Irvin and Scott Sunquist, History of the World Christian Movement: Earliest Christianity to 1453 (Maryknoll, NY: Orbis Books, 2001), 214; Sellers, xi, 4; see generally St. Cyril of Alexandria, On the Unity of Christ, trans. John Anthony McGuckin (Crestwood, NY: St. Vladimir’s Seminary Press, 1995).
 Sellers, xi, 10-11; Adrian Fortescue, The Lesser Eastern Churches, 3rd ed., The Eastern Churches Trilogy (Piscataway, NJ: Gorgias Press, 2001), 51, 78-87.
 Irvin and Sunquist, 214; W. A. Wigram, The Separation of the Monophysites (London: The Faith Press, 1923), 5, 45. Such sentiment crops up in Cyril’s writing. Consider, for example, “The Greeks, on the other hand, are wholly incapable of grasping the profundity of the mystery, for they think it is foolishness on our part to say that Christ died for the life of the world.” St. Cyril of Alexandria, 130.
 Sellers, 254.
 Lynn H. Cohick, “Jews and Christians,” in The Routledge Companion to Early Christian Thought, ed. D. Jeffrey Bingham (New York: Routledge, 2010), 71-72. This atmosphere was not limited to the Eastern Roman Empire but was common throughout the ancient world. Ibid.
 See Price and Gaddis, 1:6-7. This explains why secular authorities turned so sharply against Athanasius just a decade after Nicaea for his refusal to reconcile with the Arians. Ibid., 1:5.
 Ibid., 1:23. Cyril and John’s Formula of Reunion recognized that, though the Antiochenes affirmed “two natures,” they did not divide the Person of Christ or deny Mary the title “Theotokos,” as Nestorius had done. Sellers, xi, 23; Price and Gaddis, 1:23.
 Sellers, xii, 212; Price and Gaddis, 1:25.
 Sellers, 63, 68-69; Price and Gaddis, 1:28.
 Sellers, 32, 69.
 Price and Gaddis, 1:29-30; Sellers, 73-74.
 “Session II,” 2:15, 23; Sellers, 74; Price and Gaddis, 1:29-30.
 Price and Gaddis, 1:28; Sellers, 76.
 Sellers, xi, 3-4.
 Ibid., 3; Price and Gaddis, 1:14. This tension played out in the even earlier dispute between Theophilus of Alexandria and John Chrysostom. Sellers, 3-4.
 Sellers, 6. Indeed, Antiochene apostolic claims to authority were arguably stronger than Rome’s, since Peter and Paul had both preached there first. Price and Gaddis, 1:13.
 Price and Gaddis, 1:13.
 Ibid., 1:12. The character of Juvenal, Bishop of Jerusalem, fits the narrative of Chalcedon as a cynical powerplay much better than Dioscorus. Juvenal had made the elevation of his bishopric to patriarchate status his raison d’etre. Such an elevation, however, would have entailed the acquisition of authority over large areas of Syria, Palestine, and Arabia, which had traditionally fallen under Antiochene jurisdiction. Juvenal had previously allied himself with Cyril at the first Ephesian council and then with Dioscorus at the second. He switched sides at Chalcedon, however, but only after sensing which way that Council was going. He obtained three Palestinian provinces as a result of his turncoat efforts, calling into question the strength of his theological convictions. Ibid., 1:15. Dioscorus’ refusal to compromise, even at the cost of his position, however, suggests him to be a true believer.
 Ibid., 1:10-11.
 Sellers, 74.
 Ibid., xii.
 Ibid., 82-83.
 The Alexandrian school Cyril and Dioscorus led “started from the thought of the unquestioned unity of Christ, and then said as much about the duality as seemed reconcilable with that postulate.” Wigram, 6. Those of the Antiochene school, however, “started from the admitted duality, and proceeded thence to say what could be said on the matter of the unity.” Ibid.; Sellers, 8. There is a significant nuance to the argument, such that their two positions may represent a distinction without a difference. See ibid., 170; Sergey Trostyanskiy, “Healing the Post-Chalcedonian Schism,” International Journal for the Study of the Christian Church 15, no. 3 (2015): 171; “Agreed Statement by the Anglican-Oriental Orthodox International Communion,” updated 13–17 October 2014, accessed October 29, 2019, https://www.anglicancommunion.org/media/103502/anglican-oriental-orthodox-agreed-statement-on-christology-cairo-2014.pdf.; note 47 below. Indeed, Cyrils’s statements, “Well, Godhead is one thing, and manhood is another thing, considered in the perspective of their respective and intrinsic beings, but in the case of Christ they came together in a mysterious and incomprehensible union without confusion or change,” and “To say that he suffered does not disgrace to him, for he did not suffer in the nature of the godhead, but in his own flesh,” sound like something Leo easily could have written. St. Cyril of Alexandria, 77, 114-15; see note 3 above.
 Sellers, xii, 78-79; Price and Gaddis, 1:29-30. After the conclusion of Tome’s reading at the Council of Chalcedon, the bishops exclaimed, “This is the faith of the fathers. Why was this not read out at Ephesus? Dioscorus concealed it.” “Session II,” 2:24-25.
 Price and Gaddis, 1:32-33.
 Ibid.; Sellers, 82.
 Sellers, xii, 78; Price and Gaddis, 1:37-39.
 Sellers, 88-90; see also Pope Leo, “Pope Leo to Marcian (26 June 451),” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 1:100.
 Sellers, 93.
 Ibid., 96; Price and Gaddis, 1:38. Sellers speculates that the East and West would have gone their separate ways, with the East upholding the Second Ephesian Council and continuing to speak of “one nature,” and the West preserving the Tertullian view of two natures in one person. Sellers, 96-97. A split from a united East at such an early time over a significant theological point on the person of Christ would have weakened the then-nascent claim of universal papal jurisdiction. Therefore, the modern papacy may not have developed in the manner that it did and could have perhaps taken on a more primus inter pares form in the West.
 Sellers, xii, 63. Indeed, the Emperor had the remains of Flavian, the Bishop of Constantinople that the still-sitting Alexandrian bishop had condemned, brought back to the capital and buried in the Basilica of the Apostles, the resting place of former Constantinopolitan bishops and Constantine himself. Ibid., 97-98.
 Price and Gaddis, 1:38-39; Sellers, 99. The legitimacy of Ephesus II was being called into question, not for its theology, but for the brutal violence that accompanied its proceedings. Price and Gaddis, 1:38-39.
 Emperor Marcian, “Marcian to the Bishops (23 May 451),” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 1:98; Sellers, 98, xi. By this point, Pope Leo had come to oppose the meeting of another ecumenical council. He thought the bishops should simply repent of their mistake at Ephesus II and subscribe to his Tome. Ibid., 99-101; Decrees of the Ecumenical Councils, ed. Norman P. Tanner, 2 vols., vol. 1 (Washington, D.C.: Georgetown University Press, 1990), 1:75. Nonetheless, Leo accepted the decision and sent two delegates to represent him. Sellers, 99-101.
 Sellers, 102-04. Chalcedon would become and remain the best-attended ecumenical council in history until, appropriately, Vatican I surpassed it in 1869. Richard Price, “Truth, Omission, and Fiction in the Acts of Chalcedon,” in Chalcedon in Context, ed. Richard Price and Mary Whitby (Liverpool: Liverpool University Press, 2009), 103.
 “Session II,” 2:14.
 Ibid., 2:24-25.
 Irvin and Sunquist, 215; Price and Gaddis, 1:42.
 Sellers, 128.
 Wigram, 16.
 Price and Gaddis, 1:1; Sellers, xvi; Trostyanskiy, 164.
 Miaphysite is the preferred term, as monophysite implies Eutychianism, which Oriental Orthodoxy rejects. “Agreed Statement,” 5. The term “monophysite,” however, has become a predominant manner by which to refer to the Oriental Orthodox Church and therefore pervades the literature
 Irvin and Sunquist, 198, 214-15; Sellers, 56; Popa, 15; Wigram, 5, 45.
 Price and Gaddis, 1:55. Justinian’s attempt to reconcile the miaphysites by condemning three long-dead Antiochene teachers—Theodore of Mopsuestia, Theodoret of Cyrrhus, and Ibas of Ecessa—led to the Second Council of Constantinople, to no one’s great satisfaction. Ibid., 1:54. The Third Council of Constantinople, the sixth ecumenical Council and the final council to attempt reconciliation, affirmed that Christ had both a human and divine will, a controversy resulting from a misguided imperial attempt at reconciliation in the face of overt political concerns: Persian and Arab wars. Ibid., 1:55; Sellers, 345-46; Wigram, 13.
 Irvin and Sunquist, 215; Sellers, xvi; Trostyanskiy, 168; Wigram, 143-44. Eventually, coercive efforts to bring Egypt into unity with the rest of the Church were abandoned to stave off a potential revolt. Ibid., 94. Sympathies for the miaphysite position were so great at times in the Empire that it is incredible that Chalcedon eventually took hold. The controversial twenty-eighth canon may have preserved Chalcedon’s influence, as the bishops of Constantinople had an incentive to support a council that had so elevated their status. Sellers, 294; Wigram, 9, 53; see also note 61 below. Had Leo gotten his way at Chalcedon concerning the twenty-eighth canon, see note 60 below, his theological position may have eventually lost the day, and the history of Christian theology, both with regard to Christology and the papacy, may have taken an entirely different course. The schism between Oriental and Eastern Orthodox Church may not have been permanent, and the papacy may have faced a united Eastern opposition from two great sees against claims of universal papal jurisdiction, thereby perhaps forestalling or preventing the full development of the idea into what it would eventually become. Finally, while impossible to know, a theologically united East may have hindered Muslim expansion into miaphysite territories. Lamin Sanneh has argued that the Arabs, a nomadic people with pragmatic concerns, had little patience for the speculative philosophical musings of the Eastern Church. Lamin Sanneh, Disciples of All Nations: Pillars of World Christianity (Oxford: Oxford University Press, 2008), 63. Had Chalcedon been a paragon of reconciliation and Christian love, rather than a manufacturer of aggressive anathematizations over “theological hair-splitting,” perhaps Christianity would have been well received in the Arab world and the course of history dramatically different. Ibid., 65. The mind can run wild considering the potential butterfly effect of this one canon.
 Wigram, 92-93.
 Emperor Marcian, “Marcian to Pope Leo (September 450),” 1:92-93.
 Sellers, 217.
 Price and Gaddis, 1:67.
 Ibid., 11. The Roman Catholic Church would make this understanding of papal authority over councils official at the First Vatican Council, where it affirmed that the Pope possesses infallibility when speaking ex cathedra on matters of faith and doctrine and that “such definitions of the Roman Pontiff are of themselves, and not by the consent of the Church, irreformable.” Decrees of the Ecumenical Councils, 2 vols., vol. 2, ed. Norman P. Tanner (Washington, D.C.: Georgetown University Press, 1990), 2:816. Indeed, the suggestion that the Council of Chalcedon “did not accept Pope Leo the Great’s letter on the two natures of Christ until it had examined it,” caused consternation and was not reflected in Vatican I’s final decrees. John W. O’Malley, Vatican I: The Council and the Making of the Ultramontane Church (Cambridge, MA: Harvard University Press, 2018), 201.
 Price and Gaddis, 1:11.
 Du Bose, 263. Indeed, the papacy continues to point to Chalcedon as an example of the appropriate homage due to “Roman primacy.” The Holy See, “Sempiternus Rex Christus: Encyclical of Pope Pius XII on the Council of Chalcedon to the Venerable Brethren, the Patriarchs, Primates, Archbishops, Bishops, and Other Ordinaries in Peace and Communion with the Apostolic See,” (1951): 2. https://w2.vatican.va/content/pius-xii/en/encyclicals/documents/hf_p-xii_enc_08091951_sempiternus-rex-christus.pdf.
 “Session XVI, 1 November,” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 3:76; Price and Gaddis, 1:50; note 21 above.
 Sellers, 127-28.
 Pope Leo, “Pope Leo to Marcian (21 March 453),” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 2:151-52; Price and Gaddis, 1:51; Anatolius of Constantinople, “Anatolius of Constantinople to Pope Leo (December 451),” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 2:141; Emperor Marcian, “Marcian to Pope Leo (15 February 453),” in The Acts of the Council of Chalcedon (Liverpool: Liverpool University Press, 2005), 2:150. Rome would not accept Canon 28 until 1215 and then only “to ensure the authority of the then Latin patriarch of Constantinople,” a complex story all of its own. Judith Herrin, “The Quinisext Council (692) as a Continuation of Chalcedon,” in Chalcedon in Context, ed. Richard Price and Mary Whitby (Liverpool: Liverpool University Press, 2009), 155.
 Price and Gaddis, 1:50. Sharing the consternation of his Alexandrian rivals before him, Leo makes it a point to remind the Emperor that Constantinople is not an apostolic see, the only great patriarchate suffering this handicap. Pope Leo, “Pope Leo to Marcian (22 May 452),” 2:144; note 20 above. The Council additionally empowered the bishop of Constantinople to appoint bishops outside his realm, including lands outside the Empire. “Session XVI,” 76. It is easy to see why Rome, a see claiming universal jurisdiction, would find this problematic.
 Price and Gaddis, 1:15.
 Trostyanskiy, 171.
 While the history leading to the Great Schism is complex and not entirely the result of Chalcedon, any evaluation of the causes of the schism must view Chalcedon and its fallout as foundational.