Council of Chalcedon

Council of Chalcedon

The Council of Chalcedon
Convoked	Emperor Marcian and Empress Saint Pulcheria
Dates	8 October–1 November 451
Location	Chalcedon, Bithynia
Pope	Saint Leo I the Great
Attendance	More than 500 bishops, overwhelmingly from the East
Presidency	Papal legates in doctrinal sessions; imperial commissioners directed procedure
Principal acts	Definition of Faith, reception of Leo's Tome, and disciplinary canons

The Council of Chalcedon was the fourth ecumenical council of the Catholic Church, held in 451 to confess the one Lord Jesus Christ in two complete natures, divine and human, without confusion, change, division, or separation.

Authority level: Authoritative doctrine

From Ephesus to Chalcedon

Unity and distinction after 431

Ephesus had defended the one personal subject of the Incarnation against Nestorius. The Formula of Reunion in 433 also confessed Christ as perfect God and perfect man, consubstantial with the Father in divinity and with humanity in humanity. Yet Alexandrian and Antiochene parties continued to suspect one another. Expressions associated with Cyril of Alexandria could be interpreted either as protecting the one incarnate subject or, when detached from his complete teaching, as allowing the humanity to lose its integrity after union.

The Church needed language that would hold together both truths already present in the received faith: the eternal Son alone is the personal subject, and the divinity and humanity remain complete, unconfused realities. Chalcedon's definition was not a retreat from Ephesus or a compromise between truth and heresy. It placed Cyril, Leo, the Nicene Creed, and the reunion formula within one rule of faith.

Eutyches and the synod of 448

Eutyches, an elderly archimandrite at Constantinople, opposed Nestorian tendencies but was accused of teaching that Christ's humanity was not consubstantial with humanity after the union or that two natures existed before the union and one afterward. At a local synod in 448, Flavian of Constantinople pressed him to confess the one Christ in two natures. Eutyches gave evasive or unacceptable answers and was deposed.

Eutyches appealed to influential supporters, including Dioscorus of Alexandria and the imperial court. Pope Leo I examined the case through correspondence with Flavian and composed the Tome to Flavian. The Tome confesses one person of the Word acting in both natures: each form performs what is proper to it in communion with the other. Its balanced account opposed both division of the subject and confusion of the natures.

The Second Council of Ephesus

Emperor Theodosius II summoned another council to Ephesus in 449 under Dioscorus. Pope Leo sent legates and requested that his Tome be read. Dioscorus controlled the proceedings, restored Eutyches, condemned Flavian and Eusebius of Dorylaeum, and prevented a fair hearing of the Roman case. Soldiers and militant monks intimidated the bishops. The papal deacon Hilary escaped after voicing the Latin protest Contradicitur. Flavian died soon afterward following brutal treatment.

Leo rejected the assembly and called it a latrocinium, a robber council. Its formal imperial convocation and broad attendance did not make it ecumenical, because it violated justice, suppressed apostolic teaching, and lacked communion with the Roman Pontiff. The episode is a decisive example against defining ecumenicity by imperial designation or numbers alone.

Theodosius upheld the decisions, but his death in 450 changed the political situation. Pulcheria and Marcian favored a new settlement and restored communion with Leo. Marcian summoned bishops first to Nicaea and then, so that the imperial government could remain near the proceedings, transferred the meeting to Chalcedon across the Bosporus from Constantinople.

Convocation and assembly

The council opened on 8 October 451 in the basilica of Saint Euphemia. Estimates range above five hundred and often near six hundred bishops, making it the largest ancient council, though nearly all participants were eastern. Paschasinus of Lilybaeum, Lucentius, and the priest Boniface represented Pope Leo. Anatolius of Constantinople, Maximus of Antioch, Juvenal of Jerusalem, and other major eastern bishops attended. Imperial commissioners and senators occupied a prominent place and kept order, framed questions, and required votes.

The papal legates asserted ecclesiastical presidency in Leo's name, while the commissioners directed the external conduct of sessions. This dual arrangement resists simple modern analogies. The bishops deliberated and subscribed doctrinal and canonical judgments; the emperor secured assembly and enforcement; the pope's legates guarded Roman communion and the Tome. Catholic recognition rests on the conciliar definition as confirmed by Leo, not on treating every intervention by court officials as magisterial.

The council held a series of sessions through 1 November. The surviving acts are unusually extensive because proceedings from Constantinople in 448 and Ephesus in 449 were read aloud and transcribed. They preserve acclamations, documentary dossiers, individual votes, and procedural conflict. They must still be read critically: public acclamations could express genuine conviction, group pressure, liturgical rhetoric, or strategic alignment at once.

Proceedings

Dioscorus and the acts of 449

At the first session the legates demanded that Dioscorus not sit as a judge because he stood accused. The council read the record of Flavian's synod and the second Ephesian council, exposing coercion and the refusal to hear Leo's letter. Bishops who had supported Dioscorus pleaded fear and disowned the earlier action. The commissioners and assembly deposed several leaders from their positions pending judgment.

At the third session Dioscorus refused repeated summonses. The legates and bishops deposed him for canonical disobedience, his conduct at Ephesus, reception of Eutyches, and separation from Leo's communion. The sentence did not rest on a fully litigated finding that every formula Dioscorus personally used was Eutychian. This distinction matters in modern dialogue, although it does not rehabilitate his violent administration of 449 or undo the council's lawful judgment.

The Tome and the rule of faith

The bishops read the creeds of Nicaea and Constantinople, Cyril's second letter to Nestorius and letter to John of Antioch, and Leo's Tome. They compared the Tome with Cyril rather than accepting it as an isolated western document. After scrutiny they acclaimed its orthodoxy, famously declaring that Peter had spoken through Leo. The acclamation expresses recognition of Petrine teaching in the pope's doctrinal witness; it does not imply that the bishops suspended theological judgment.

Many bishops initially resisted drafting a new formula because they believed the received documents sufficient and because Ephesus had forbidden a rival creed. The commissioners, acting under imperial instructions, insisted that the conflict required an explicit definition. A committee produced a text that incorporated the earlier creeds and letters while adding the precise symmetrical language needed to exclude both Eutychian confusion and Nestorian division.

The Definition of Faith

One and the same Christ

The definition repeatedly identifies one and the same Son, our Lord Jesus Christ. He is perfect in divinity and perfect in humanity, truly God and truly man, possessing a rational soul and body. He is consubstantial with the Father according to divinity and consubstantial with us according to humanity, like us in all things except sin. Eternally begotten from the Father according to divinity, he was born in the last days from the Virgin Mary, Theotokos, according to humanity.

This parallel construction joins Nicaea and Ephesus. The Son's divine identity is the reason his human birth is the birth of the Theotokos; the integrity of his rational human nature is the reason his obedience, suffering, death, and resurrection are genuinely human. The definition refuses both a creaturely Christ and a humanity used as an appearance or instrument without its own natural powers.

In two natures

The one Christ is acknowledged in two natures, without confusion, change, division, or separation. Without confusion and without change protect the distinction and integrity of divinity and humanity. Without division and without separation protect the one person and hypostasis. The distinction of natures is not abolished by union; the property of each is preserved as both concur in one person and one hypostasis.

Nature answers what Christ is; person or hypostasis answers who he is. The formula does not place a divine person beside a human person. There is only the eternal Son. Nor does it turn the natures into separable actors. The one Son knows, wills, acts, suffers, and saves through the natural capacities proper to his divinity and humanity. Later councils would draw out this logic against new forms of division or absorption.

Chalcedon's four adverbs are deliberately apophatic: they set boundaries around a mystery no conceptual scheme can exhaust. The hypostatic union is unique. It neither mixes God and humanity into a third kind of being nor places them in a moral partnership. Because the natures remain what they are in the one person, Christ can reveal the Father as God and offer perfect human obedience on humanity's behalf.

Other judgments and restorations

The council examined the cases of Theodoret of Cyrrhus and Ibas of Edessa, whose writings and alliances had aroused suspicion after Ephesus. Theodoret anathematized Nestorius and was restored to his see. Ibas was restored after review of his case and a disputed letter to Maris. These personal judgments later became central to the Three Chapters controversy because opponents of Chalcedon claimed that the fourth council had honored Nestorian teachers.

Chalcedon did not canonize every sentence written by a restored bishop. Its restorations followed required professions and judgments about communion. Constantinople II would later condemn Theodore of Mopsuestia, certain anti-Cyrillian writings of Theodoret, and the letter attributed to Ibas while explicitly maintaining Chalcedon's authority. The distinction between a person's restoration and approval of every work is essential to continuity between the councils.

The council also ratified an agreement between Antioch and Jerusalem that recognized Juvenal's jurisdiction over the three Palestinian provinces and left Phoenicia and Arabia to Antioch. This settlement contributed to Jerusalem's emergence as the fifth patriarchal see. Like the ranking of Constantinople, it belonged to ecclesiastical discipline rather than the Christological definition.

The disciplinary canons

Chalcedon's canonical legislation addresses simony, episcopal and clerical discipline, monasteries, property, litigation, transfers, provincial administration, and the stability of ecclesiastical office. It subjects monks and monasteries to the diocesan bishop, forbids clerics from secular business for gain, protects church goods after a bishop's death, requires provincial synods, and provides procedures for disputes involving bishops and metropolitans.

Different collections number the canons differently. The Greek tradition ordinarily counts twenty-eight, while ancient Latin collections did not receive canon 28. Material sometimes numbered 29 and 30 belongs to session minutes rather than an identical canonical series. Responsible citation therefore identifies the textual tradition instead of assuming one uncontested list.

The canons reveal an increasingly complex imperial Church and the effort to protect ministry from patronage, violence, and jurisdictional competition. They remain important historical and canonical witnesses, but their juridical force differs from the irreformable definition of faith and from current canon law. A council's authority does not flatten doctrine, discipline, case judgments, and administrative settlements into one grade.

Canon 28 and Roman primacy

Canon 28, adopted after the papal legates had withdrawn from the session, appealed to Constantinople's status as New Rome to grant it equal privileges after Old Rome and jurisdiction over the dioceses of Pontus, Asia, and Thrace, including ordinations among peoples beyond imperial frontiers. Its supporters treated civil dignity as the precedent for ecclesiastical rank and extended the direction of Constantinople I's third canon.

The legates protested, and Pope Leo rejected the canon. He argued that the privileges of the great sees rested on apostolic and Nicene order, not a city's political elevation, and that Alexandria and Antioch could not be diminished by imperial convenience. Leo confirmed the council's faith and accepted its legitimate discipline while withholding confirmation from canon 28. The canon therefore cannot be cited as a dogmatic act received by Rome.

Constantinople nevertheless acquired the practical position of second see in the imperial Church, and later Catholic councils recognized that patriarchal order. Catholic doctrine can acknowledge this historical development while maintaining that the Bishop of Rome's universal primacy derives from succession to Peter rather than the former civil greatness of Rome. The conflict is important for Catholic-Orthodox study of primacy and synodality in the first millennium.

Reception and schism

Imperial enforcement and resistance

Marcian promulgated and enforced Chalcedon's decisions. Strong resistance arose in Egypt, parts of Syria, Armenia, and Palestine. Many believers perceived the phrase in two natures as a betrayal of Cyril or a restoration of Nestorian division, while political, linguistic, monastic, and regional conflicts intensified doctrinal suspicion. Imperial coercion and rival episcopal successions hardened divisions that cannot be explained by vocabulary alone.

Later emperors tried compromise. Zeno's Henotikon of 482 avoided Chalcedon's disputed language but produced the Acacian schism with Rome. Justinian I defended Chalcedon through a more explicitly Cyrillian interpretation, leading to Constantinople II. Chalcedonian and non-Chalcedonian hierarchies became enduring ecclesial bodies, particularly after Arab conquest weakened imperial capacity to impose uniformity.

Oriental Orthodox reception

The Coptic, Syriac, Armenian, Ethiopian, Eritrean, and Malankara Orthodox Churches do not receive Chalcedon as ecumenical. They commonly describe their Christology as miaphysite, following Cyril's formula of one incarnate nature of the Word, and reject the idea that Christ's humanity is absorbed or confused. Applying Monophysite indiscriminately to their present confession mistakes them for the Eutychian error they also reject.

Catholic faith still receives Chalcedon's definition as true and binding. Modern dialogue has nevertheless shown that many inherited condemnations struck formulas understood differently across languages and schools. Recognizing a shared orthodox intention does not declare the ancient council mistaken, erase ecclesiological disagreements, or create full communion. It separates genuine dogmatic contradiction from misunderstandings that no longer justify division.

Modern Christological agreements

In 1973 Pope Saint Paul VI and Pope Shenouda III of the Coptic Orthodox Church confessed together that Christ is perfect God and perfect man, with divinity united to humanity in a real and perfect union without mingling, confusion, alteration, division, or separation. Comparable declarations with Syriac and Armenian Orthodox heads professed the same Lord while acknowledging historical differences in terminology and interpretation around Chalcedon.

These agreements confirm the doctrinal purpose of Chalcedon rather than replacing it. Their language echoes the four adverbs and the one personal subject. They also require humility in historical narration: communities that rejected the council are not thereby shown to worship a different Christ today, and Chalcedonian Christians must not turn a precise condemnation of Eutyches into a polemical label for every Oriental tradition.

Remaining obstacles include the reception of councils and fathers, mutual anathemas, ecclesiology, sacramental communion, and the universal ministry of the Bishop of Rome. Christological agreement supplies a necessary basis for resolving them but does not make visible unity automatic. The Catholic goal is restored full communion in the truth, not a diplomatic statement that contradictions never mattered.

Authority and legacy

Pope Leo confirmed Chalcedon's Definition of Faith, and the Catholic Church receives it as an infallible act of the solemn Magisterium. Its claim is permanently normative: the one divine person of Christ subsists in a complete divine nature and a complete human nature. The council's case judgments and canons possess the authority proper to those acts, with canon 28 notably lacking Roman confirmation.

Constantinople II, Constantinople III, and later Christology interpret rather than overturn Chalcedon. The fifth council makes explicit that the one hypostasis is the Word, one of the Trinity; the sixth confesses two natural wills and operations. Catholic theology therefore reads Chalcedon within the whole conciliar sequence, avoiding both a static repetition of 451 and any development that contradicts its boundaries.

Chalcedon's legacy reaches beyond technical vocabulary. Christian salvation depends on the truth it guards. Because Christ is fully divine, he communicates God's life; because he is fully human, his obedience, suffering, and risen humanity are truly ours; because he is one person, the saving acts belong to the eternal Son. The definition remains a rule for preaching, sacramental worship, Marian doctrine, anthropology, and hope for humanity's communion with God.

From the 1913 Catholic Encyclopedia

Council of Chalcedon — The Fourth Ecumenical Council, held in 451, from 8 October until 1 November inclusive, at Chalcedon, a city of Bithynia in Asia Minor. Its principal purpose was to assert the orthodox Catholic doctrine against the heresy of Eutyches and the Monophysites, although ecclesiastical discipline and jurisdiction also occupied the council's attention.

Scarcely had the heresy of Nestorius concerning the two persons in Christ been condemned by the Council of Ephesus, in 431, when the opposite error of the Nestorian heresy arose. Since Nestorius so fully divided the Divine and the human in Christ that he taught a double personality or a twofold being in Christ, it became incumbent on his opponents to emphasize the unity in Christ and to exhibit the God-man, not as two beings but as one. Some of these opponents in their efforts to maintain a physical unity in Christ held that the two natures in Christ, the Divine and the human, were so intimately united that they became physically one, inasmuch as the human nature was completely absorbed by the Divine. Thus resulted one Christ not only with one personality but also with one nature. After the Incarnation, they said, no distinction could be made in Christ between the Divine and the human. The principal representatives of this teaching were Dioscurus, Patriarch of Alexandria, and Eutyches, an archimandrite or president of a monastery outside Constantinople. The Monophysitic error, as the new error was called (Gr. mone physis, one nature), claimed the authority of St. Cyril, but only through a misinterpretation of some expressions of the great Alexandrine teacher.

The error of Eutyches was first detected by Domnus, Patriarch of Antioch. a formal accusation was preferred against the former by Eusebius, Bishop of Dorylaeum (Phrygia), at a synod of Constantinople in November of that year. This synod declared it a matter of faith that after the Incarnation, Christ consisted of two natures (united) in one hypostasis or person; hence there was one Christ, one Son, one Lord. Eutyches, who appeared before this synod, protested, on the contrary, that before the Incarnation there were two natures, but after the union there was only one nature in Christ; and the humanity of Christ was not of the same essence as ours. These statements were found contrary to Christian orthodoxy; Eutyches was deposed, excommunicated, and deprived of his station in the monastery. He protested, and appealed for redress to Pope Leo I (440-61), to other distinguished bishops, and also to Theodosius II. Bishop Flavian of Constantinople informed Pope Leo and other bishops of what had occurred in his city. Eutyches won the sympathy of the emperor; through the monk's representations and those of Dioscurus, Patriarch of Alexandria, the emperor was induced to invoke a new council, to be held at Ephesus. Pope Leo, Dioscurus, and a number of bishops and monks were invited to attend and investigate anew the orthodoxy of Eutyches. The pope was unable to go, but sent three delegates as his representatives and bearers of letters to prominent personages of the East and to the impending synod. Among these letters, all of which bear the date of 13 June, 449, is one known as the "Epistola Dogmatica", or dogmatic letter, of Leo I, in which the pope explains the mystery of the Incarnation with special reference to the questions raised by Eutyches. Thus, he declares that after the Incarnation what was proper to each nature and substance in Christ remained intact and both were united in one person, but so that each nature acted according to its own qualities and characteristics. As to Eutyches himself, the pope did not hesitate to condemn him. The council was held at Ephesus, in August, 449. Only the friends and partisans of Dioscurus and Eutyches were allowed to have a voice. The Alexandrine patriarch presided; he ignored the papal delegates, would not permit the letters of Pope Leo, including the "Epistola Dogmatica", to be read in the assembly. Eutyches was declared orthodox and reinstated in his priestly and monastic office. On the other hand, Flavian of Constantinople and Eusebius of Dorylaeum were deposed. The former was banished, and died shortly afterwards in consequence of ill-treatment; he was succeeded by the deacon Anatolius, a partisan of Dioscurus. Owing to the gross violence of Dioscurus and his partisans, this assembly was called by Leo I the "Latrocinium", or Robber Council, of Ephesus, a name that has since clung to it.

Theodosius II, who sympathized with Eutyches, approved these violent deeds; Leo I, on the other hand, when fully informed of the occurrences at Ephesus, condemned, in a Roman synod and in several letters, all the Acts of the so-called council. He refused also to recognize Anatolius as lawful Bishop of Constantinople, at least until the latter would give satisfaction concerning his belief. At the same time he requested the emperor to order the holding of a new council in Italy, to right the wrongs committed at Ephesus. As a special reason for the opportuneness, and even necessity, of the new council, he alleged the appeal of the deposed Flavian of Constantinople. Theodosius, however, positively declined to meet the wishes of the pope. At this stage the sudden death of the emperor (28 July, 450) changed at once the religious situation in the East. Theodosius was succeeded by his sister, Pulcheria, who offered her hand, and with it the imperial throne, to a brave general named Marcian (450-57). Both Marcian and Pulcheria were opposed to the new teaching of Dioscurus and Eutyches; and Marcian at once informed Leo I of his willingness to call a new council according to the previous desire of the pope. In the meantime conditions had changed. Anatolius of Constantinople, and with him many other bishops, condemned the teaching of Eutyches and accepted the dogmatic epistle of Pope Leo. Any new discussions concerning the Christian Faith seemed therefore superfluous. Western Europe, moreover, was in a state of turmoil owing to the invasion of the Huns under Attila, for which reason most of the Western bishops could not attend a council to be held in the East. Leo I therefore protested repeatedly against a council and wrote in this sense to the Emperor Marcian, the Empress Pulcheria, Anatolius of Constantinople, and Julian of Cos; all these letters bear the date of 9 June, 451. Meanwhile, 17 May, 451, a decree was issued by Marcian -- in the name also of the Western Emperor Valentinian III (425-55) -- ordering all metropolitan bishops with a number of their suffragan bishops to assemble the following September at Nicaea in Bithynia, there to hold a general council for the purpose of settling the questions of faith recently called in doubt.

Though displeased with this action, the pope nevertheless agreed to send his representatives to Nicaea. He appointed as legates Paschasinus, Bishop of Lilybaeum (Marsala) in Sicily, Lucentius, also a bishop, Julian, Bishop of Cos, and two priests, Boniface and Basil; Paschasinus was to preside over the coming council in the pope's place. On 24 and 26 June, 451, Leo I wrote letters to the Emperor Marcian, to his legate Paschasinus, to Anatolius of Constantinople, to Julian of Cos, and to the synod itself, in which he expressed the desire that the decrees of the synod should be in conformity with his teaching as contained in the aforesaid dogmatic epistle. A detailed instruction was also given to the papal legates, which contained directions for their guidance in the council; this document, however, has perished, with the exception of two fragments preserved in the Acts of the council. In July the papal legates departed for their destination. Many bishops arrived at Nicaea during the summer, but the opening of the council was postponed owing to the emperor's inability to be present. Finally, at the complaint of the bishops, who grew weary of waiting, Marcian requested them to come to Chalcedon, in the near vicinity of Constantinople. This was done, and the council opened at Chalcedon on 8 October.

In all likelihood an official record of the proceedings was made either during the council itself or shortly afterwards. The assembled bishops informed the pope that a copy of all the "Acta" would be transmitted to him; in March, 453, Pope Leo commissioned Julian of Cos, then at Constantinople, to make a collection of all the Acts and translate them into Latin. Very ancient versions of the Acts, both in Greek and Latin, are still extant. Most of the documents, chiefly the minutes of the sessions, were written in Greek; others, e.g. the imperial letters, were issued in both languages; others, again, e.g. the papal letters, were written in Latin. Eventually nearly all of them were translated into both languages. The Latin version, known as the "versio antiqua", was probably made about 500, perhaps by Dionysius Exiguus. About the middle of the sixth century the Roman deacon Rusticus then in Constantinople with Pope Vigilius (537-55), made numerous corrections in the "versio antiqua", after comparison with Greek manuscripts of the Acts, chiefly with those of the "Acoemetae" monastery either at Constantinople or at Chalcedon. As to the number of sessions held by the Council of Chalcedon there is a great discrepancy in the various texts of the Acts, also in the ancient historians of the council. Either the respective manuscripts must have been incomplete; or the historians passed over in silence several sessions held for secondary purposes. According to the deacon Rusticus, there were in all sixteen sessions; this division is commonly accepted by scholars, including Bishop Hefele, the learned historian of the councils. If all the separate meetings were counted, there would be twenty-one sessions; several of these meetings, however, are considered as supplementary to preceding sessions. all the sessions were held in the church of St. Euphemia, Martyr, outside the city and directly opposite Constantinople. The exact number of bishops present is not known. The synod itself, in a letter to Pope Leo, speaks of 520, while Pope Leo says there were 600; according to the general estimate there were 630, including the representatives of absent bishops. No previous council could boast of so large a gathering of bishops, while the attendance at later councils seldom surpassed or even equalled that number. The council, however, was not equally representative as to the countries whence came so many bishops. Apart from the papal legates and two African bishops, practically all the bishops belonged to the Eastern Church. This, however, was well represented; the two great civil divisions (prefectures), of the Orient and of Illyricum, comprising Egypt, the Orient (including Palestine), Pontus, Asia, Thrace, Dacia, and Macedonia, sent their contingents. The more prominent among the Eastern bishops were Anatolius of Constantinople, Maximus of Antioch, Dioscurus of Alexandria, Juvenal of Jerusalem, Thalassius of Caesarea in Cappadocia, Stephen of Ephesus, Quintillus of Heraclea, and Peter of Corinth. The honour of presiding over this venerable assembly was reserved to Paschasinus, Bishop of Lilybaeum, the first of the papal legates, according to the intention of Pope Leo I, expressed in his letter to Emperor Marcian (24 June, 451). Shortly after the council, writing to the bishops of Gaul, he mentions that his legates presided in his stead over the Eastern synod. Moreover, Paschasinus proclaimed openly in presence of the council that he was presiding over it in the name and in the place of pope Leo. The members of the council recognized this prerogative of the papal legates. When writing to the pope they professed that, through his representatives, he presided over them in the council. In the interest of order and a regular procedure the Emperor Marcian appointed a number of commissioners, men of high rank, who received the place of honour in the council. Their jurisdiction, however, did not cover the ecclesiastical or religious questions under discussion. The commissioners simply directed the order of business during the sessions; they opened the meetings, laid before the council the matters to be discussed, demanded the votes of the bishops on the various subjects, and closed the sessions. Besides these there were present several members of the Senate, who shared the place of honour with the imperial commissioners.

At the very beginning of the first session, the papal legates, Paschasinus at their head, protested against the presence of Dioscurus of Alexandria. Formal accusations of heresy and of unjust actions committed in the Robber Council of Ephesus were preferred against him by Eusebius of Dorylaeum; and at the suggestion of the imperial commissioners he was removed from his seat among the bishops and deprived of his vote. In order to make a full investigation of his case the Acts of the Robber Council, with those of the synod held in 448 by Flavian of Constantinople, were read in full; this occupied the whole first session. At the end the imperial commissioners declared that since Flavian of Constantinople and other bishops had been unjustly deposed by the Robber Council it would be just that Dioscurus and the leaders in that synod should now suffer the same punishment. A number of bishops agreed, but finally all declared themselves satisfied with the deposition of Dioscurus alone.

The second session (10 October) was occupied with the reading of testimonia bearing on questions of faith, chiefly those under discussion. Among them were the symbols or creeds of the Councils of Nicaea (325) and of Constantinople (381); two letters of St. Cyril of Alexandria, viz. his second letter to Nestorius and the letter written to the Antiochene bishops in 433 after his reconciliation with them; finally the dogmatic epistle of Pope Leo I. All these documents were approved by the council. When the pope's famous epistle was read the members of the council exclaimed that the faith contained therein was the faith of the Fathers and of the Apostles; that through Leo, Peter had spoken.

The third session was held 13 October; the imperial commissioners and a number of bishops were absent. Eusebius of Dorylaeum presented a new accusation against Dioscurus of Alexandria in which the charges of heresy and of injustice committed in the Robber Council of Ephesus were repeated. Three ecclesiastics and a layman from Alexandria likewise presented accusations against their bishop; he was declared guilty of many acts of injustice and of personal misconduct. At the end of the session the papal legates declared that Dioscurus should be deprived of his bishopric and of all ecclesiastical dignities for having supported the heretic Eutyches, for having excommunicated Pope Leo, and for having refused to answer the charges made against him. All the members present agreed to this proposition; and the decree of deposition was communicated to Dioscurus himself, to the Alexandrine ecclesiastics with him at Chalcedon, to the Emperors Marcian and Valentinian III, and to the Empress Pulcheria.

The fourth session, which comprised two meetings, was held on 17 and 20 October. At the request of the imperial commissioners the bishops again approved the dogmatic epistle of Pope Leo I; Juvenal of Jerusalem, Thalassius of Caesarea in Cappadocia, Eusebius of Ancyra, Eustathius of Berytus, and Basil of Seleucia in Cicilia, former partisans of Dioscurus in the Robber Council of Ephesus, were pardoned and admitted to the sessions; an investigation was made into the orthodoxy of a number of bishops from Egypt, and of a number of monks and archimandrites suspected of Eutychianism; finally a dispute between Photius of Tyre and Eustathius of Berytus concerning the territorial extent of their respective jurisdiction was adjudicated.

The most important of all the sessions was the fifth, held 22 October; in this the bishops published a decree concerning the Christian Faith, which must be considered as the specific dogmatic decree of the Fourth General Council. A special commission, consisting of the papal legates, of Anatolius of Constantinople, Maximus of Antioch, Juvenal of Jerusalem, and several others, was appointed to draw up this creed or symbol. After again approving the decrees and symbols of the Councils of Nicaea (325), Constantinople (381), and Ephesus (431), as well as the teaching of St. Cyril against Nestorius and the dogmatic epistle of Pope Leo I, the document in question declares:

We teach... one and the same Christ, Son, Lord, Only-begotten, known in two natures, without confusion, without change, without division, without separation.

After the recitation of the decree all the bishops exclaimed that such was the true faith, and that all should at once sign their names to it. The imperial commissioners announced that they would communicate to the emperor the decree as approved by all the bishops.

The sixth session (25 October) was celebrated with special solemnities; Marcian and Pulcheria were present with a great attendance, with all the imperial commissioners and the Senate. The emperor made an appropriate address; the decree of faith made in the preceding session was read again and approved by the emperor; and with joyful acclamations to the emperor and to the empress, in which they were compared to Constantine and Helena, the proceedings were closed.

The object of the council was attained in the sixth session, and only secondary matters were transacted in the remaining sessions. the seventh and eighth sessions were both held 26 October.

In the seventh an agreement between Maximus of Antioch and Juvenal of Jerusalem was approved, according to which the territory of the Patriarchate of Jerusalem was restricted to the three provinces of Palestine.

In the eighth session Theodoret of Cyrus, a former partisan of Nestorius, was compelled to condemn the name of his friend under threats of expulsion from the council. He was then reinstated in his bishopric.

The ninth and tenth sessions (27 and 28 October) dealt with the case of Ibas, Bishop of Edessa, who had been deposed on charges made by some of his ecclesiastics. The accusation proved to be unfounded and Ibas was reinstated in his office. A decision was also given to the effect that a pension should be paid by Maximus of Antioch to his deposed predecessor Domnus.

The eleventh and twelfth sessions (29 and 30 October) dealt with a conflict between Bassianus and Stephen, both raised successively but irregularly to the See of Ephesus. The council declared that a new bishop should be chosen for Ephesus, but the two aforesaid should retain their episcopal dignity and receive a pension from the church revenues of Ephesus.

The thirteenth session (30 October) decided a case of conflicting jurisdiction. Eunomius of Nicomedia and Anastasius of Nicaea both claimed metropolitan rights, at least for a part of Bithynia. The council decreed that in a province there could be only one metropolitan bishop, and in favour of the Bishop of Nicomedia.

The fourteenth session (31 October) decided the rival claims of Sabinian and Athanasius to the See of Perrha in Syria. Sabinian had been chosen in place of Athanasius deposed by an Antiochene synod in 445; later Athanasius was reinstated by the Robber Council of Ephesus. The council decreed that further investigation should be made into the charges against Athanasius, Sabinian meanwhile holding the see. If the charges should prove untrue, Athanasius should be reinstated and Sabinian receive a pension from the diocese. In the same session a letter of Pope Leo was read, and the council approved the decisions in regard to Maximus of Antioch in his conflict with Juvenal of Jerusalem, and his obligation of providing for his predecessor Domnus.

In the fifteenth session (31 October) the council adopted and approved twenty-eight disciplinary canons. The papal legates, however, as well as the imperial commissioners departed at the beginning of the session, probably foreseeing that the hierarchical status of the Bishop of Constantinople would be defined, as really occurred in canon 28.

• The first canon approved the canons passed in previous synods.

• The second established severe penalties against those who conferred ecclesiastical orders or positions for money, or received such orders or positions for money, and acted as intermediaries in such transactions.

• The third forbade secular traffic to all ecclesiastics, except in the interest of minors, orphans, or other needy persons.

• The fourth forbade the erection of a monastery or an oratory without the permission of the proper bishop; recommended to the monks a life of retirement, mortification, and prayer; and forbade the reception of a slave in a monastery without the permission of his master.

• The fifth inculcated the canons of previous synods concerning the transfer of bishops and clerics from one city to another.

• The sixth recommended that no one should be ordained except he were assigned to some ecclesiastical office. Those ordained contrary to this provision were not to exercise their order.

• The seventh forbade ecclesiastics to exercise the military art or to hold a secular office.

• The eighth decreed that the clerics of charitable homes, monasteries, or oratories of martyrs should be subject to the bishop of the territory.

• The ninth ordained that ecclesiastics should conduct their lawsuits only before the bishop, the synod of the province, the exarch, or the Bishop of Constantinople.

• The tenth forbade ecclesiastics to be enrolled in the church-registers of different cities.

• The eleventh ordained that the poor and needy, when travelling, should be provided with letters of recommendation (litterae pacificae) from the churches.

• The twelfth forbade the bishops to obtain from the emperors the title of metropolitans to the prejudice of the real metropolitan of their province.

• The thirteenth forbade to strange clerics the exercise of their office unless provided with letters of recommendation from their bishop.

• The fourteenth forbade minor clerics to marry heretical women, or to give their children in marriage to heretics.

• The fifteenth decreed that no deaconess should be ordained below the age of forty; and no person once ordained a deaconess was allowed to leave that state and marry.

• The sixteenth forbade the marriage of virgins or monks consecrated to God.

• The seventeenth ordained that the parishes in rural districts should remain under the jurisdiction of their respective bishops; but if a new city were built by the emperor, its ecclesiastical organization should be modelled on that of the State.

• The eighteenth forbade secret organizations in the Church, chiefly among clerics and monks.

• The nineteenth ordained that the bishops of the province should assemble twice a year for the regular synod.

• The twentieth forbade again the transfer of an ecclesiastic from one city to another, except in the case of grave necessity.

• The twenty-first ordained that complaints against bishops or clerics should not be heard except after an investigation into the character of the accuser.

• The twenty-second forbade ecclesiastics to appropriate the goods of their deceased bishop.

• The twenty-third forbade clerics or monks to sojourn in Constantinople without the permission of their bishop.

• The twenty-fourth ordained that monasteries once established, together with the property assigned to them, should not be converted to other purposes.

• The twenty-fifth ordained that the metropolitan should ordain the bishops of his province within three months (from election).

• The twenty-sixth ordained that ecclesiastical property should not be administered by the bishop alone, but by a special procurator.

• The twenty-seventh decreed severe penalties against the abduction of women.

• The twenty-eighth ratified the third canon of the Council of Constantinople (381), and decreed that since the city of Constantinople was honoured with the privilege of having the emperor and the Senate within its walls, its bishop should also have special prerogatives and be second in rank, after the Bishop of Rome. In consequence thereof he should consecrate the metropolitan bishops of the three civil Dioceses of Pontus, Asia, and Cappadocia.

This last canon provoked another session of the council, the sixteenth, held on 1 November. The papal legates protested therein against this canon, alleging that they had special instructions from Pope Leo on that subject, that the canon violated the prerogatives of the Patriarchs of Alexandria, Antioch, and Jerusalem, and was contrary to the canons (vi, vii) of the Council of Nicaea. Their protests, however, were not listened to; and the council persisted in retaining this canon in its Acts. With this incident the Council of Chalcedon was closed. At the closing of the sessions the council wrote a letter to Pope Leo I, in which the Fathers informed him of what had been done; thanked him for the exposition of Christian Faith contained in his dogmatic epistle; spoke of his legates as having presided over them in his name; and asked for the ratification of the disciplinary matters enacted, particularly canon 28. This letter was handed to the papal legates, who departed for Rome soon after the last session of the council. Similar letters were written to Pope Leo in December by Emperor Marcian and Anatolius of Constantinople. In reply Pope Leo protested most energetically against canon xxviii and declared it null and void as being against the prerogatives of Bishops of Alexandria and Antioch, and against the decrees of the Council of Nicaea. Like protests were contained in the letters written 22 May, 452, to Emperor Marcian, Empress Pulcheria, and Anatolius of Constantinople. Otherwise the pope ratified the Acts of the Council of Chalcedon, but only inasmuch as they referred to matters of faith. This approval was contained in letters written 21 March, 453, to the bishops who took part in the council; hence the Council of Chalcedon, at least as to the first six sessions, became an ecumenical synod, and was considered as such by all Christians, both in the time of Poe Leo and after him. The Emperor Marcian issued several edicts (7 February, 13 March, and 28 July, 452) in which he approved the decrees of the Council of Chalcedon, forbade all discussions on questions of faith, forbade the Eutychians to have priests, to live in monasteries, to hold meetings, to inherit anything, to bequeath anything to their partisans, or to join the army. The clerics among the followers of Eutyches, hitherto orthodox, and the monks of his monastery, were to be expelled from Roman territory, as once the Manichaeans were. The writings of the Eutychians were to be burned; their authors, or those who spread them, were to be punished with confiscation and banishment. Finally Eutyches and Dioscurus were both banished. The former died about that time, while the latter lived to the year 454 in Gangra in Paphlagonia.

The Council of Chalcedon with its dogmatic definition did not put an end to the controversy concerning the natures of Christ and their relation to each other. Many people in the East disliked the term person used by the council to signify the union of, or the means of uniting, the two natures in Christ. They believed that Nestorianism was thereby renewed; or at least they thought the definition less satisfactory than St. Cyril's concept of the union of the two natures in Christ (Bardenhewer, Patrologie, 2nd ed., 321-22). In Palestine, Syria, Armenia, Egypt, and other countries, many monks and ecclesiastics refused to accept the definition of Chalcedon; and Monophysites are found there to this day. (See DIOSCURUS; EUTYCHIANISM; MONOPHYSITISM.)