Ephrem the Syrian is one of the two most important fourth-century Syriac writers.1 He was born ca. 307–309 in the Roman city of Nisibis (modern-day Nusaybin in Turkey) and was likely raised as a Christian, having close relationships with the city’s bishops from his youth. He was a member of the îḥîdāyê (“single ones”), a group within the larger Christian community whose members devoted themselves to asceticism and celibacy without forming a distinct monastic community. This was a pattern of Christian living that was peculiar to Syriac-speaking regions. Ephrem also served his community as a teacher and perhaps also as a deacon. Above all, Ephrem was a writer: he wrote in multiple genres, including biblical commentaries and metrical homilies (memre), but he is especially known for his hymns (madrāse), about 400 of which are extant. In 363 Ephrem relocated to Edessa (modern-day Urfa in Turkey) when Nisibis, on the border between the Roman and Persian Empires, was ceded by the Romans to the Persians, prompting Christians to emigrate.

A number of letters of Timothy Aelurus survive in Syriac. These reveal Timothy in a more pastoral and less polemical light, as these letters are generally written to support miaphysites throughout the Roman Empire in the midst of not only their struggles to maintain their faith but also their challenges in creating a miaphysite church. One such letter was written to Claudianus. Identified as an abbot and priest, nothing more is known about him. The heading of letter (which is not part of the original letter) claims that it was written in exile from Chersonesus. If that is correct, then is dated to 464/5–475. Toward the end of the letter Timothy mentions a small treatise he wrote when summoned by the emperor (presumably to Constantinople). If this happened under Emperor Leo, it supports the dating of 464/5–475. But such a summons is otherwise unattested. If the summoning refers to when Emperor Basiliscus called Timothy to Constantinople in 475, the letter must have actually been written after his exile in Chersonesus and thus must be one of his last extant works before his death in 477. No other evidence helps to decide the issue.

Hilary of Poitiers was one of the premier theologians of the Latin West in the fourth century, along with Ambrose of Milan and Augustine of Hippo. In 356 he was banished at a synod at Béziers for his support of Athanasius and the Alexandrian bishop’s “anti-Arian” program, and exiled to Asia Minor for four years. Here Hilary became far more knowledgeable about the theological debates rocking the church, and his own theology was decisively shaped by the encounter. He was particularly influenced by the Homoiousian theology of Basil of Ancyra. Hilary attended the Council of Seleucia in 359, which promulgated a broadly Homoian creed that was given official approval, under the auspices of Emperor Constantius, at Constantinople in January 360. During his exile in the East he penned a number of theological works, including On the Trinity, against Homoian theology. Shortly after the synod in Constantinople he returned to his homeland, where he worked against those who supported Homoian theology. He died in 367 or 368.

Emperor Justinian convened the second Council of Constantinople in 553 for the sole purpose of condemning the so-called Three Chapters – the person and writings of Theodore of Mopsuestia (d. 428), certain writings of Theodoret of Cyrrhus (d. ca. 466), and the Letter to Mari the Persian attributed to Ibas of Edessa (d. 457). Why was it deemed expedient to condemn these figures and their writings a century after their deaths? The reasons are complicated and remain debated by scholars. Justinian was at least partially motivated by fostering a reconciliation of anti-Chalcedonians with the imperial, Chalcedonian church. The condemnation of the Three Chapters by a joint council of Eastern and Western bishops was probably intended to demonstrate to anti-Chalcedonians that the charge of “Nestorianism” they leveled against the imperial church was groundless.

Athanasius was bishop of Alexandria on and off for nearly fifty years, from his contested election in 328 until his death in 373. He is perhaps best known for the unflinching promotion of a theology which he claimed represented the traditional Christian viewpoints articulated at the Council of Nicaea, against Trinitarian heterodoxies he connected with Arius and those supposedly influenced by him. Various emperors irked by his ecclesio-political efforts deposed Athanasius from his see no less than five times, causing him to spend many years in exile. Though Athanasius is most famous for his defense of the Nicene doctrine of the Trinity, Christological concerns were never far from his mind and some works of his, or at least sections thereof, are even specifically Christological in focus. For example, On the Incarnation (composed ca. 328–335) is a meditation on the person of Christ and soteriology, arguing that the salvation of humanity could only be achieved through the fully divine Word becoming incarnate, whereas his Oration against the Arians 3.26–58 (early 340s) defends the reality of the incarnation of the Word against “Arian” scriptural arguments against it.

Among other things Basil of Caesarea was renowned for his preaching.1 Both as a presbyter and then a bishop, he preached on a regular basis on the various Sundays, feasts, and celebrations of the church’s liturgical calendar, as well as at synods and other ecclesiastical gatherings. Only about fifty of his homilies are extant, one of which is his Homily on the Holy Birth of Christ. Some scholars claim it is one of the earliest witnesses to the celebration of Christmas on December 25, but if not, it was probably preached on January 6 in celebration of the feast of the Theophany (also known as Epiphany). The year cannot be determined with any precision, but Basil probably delivered it during his episcopacy, 370–378, which is roughly the same period in which Letters 261 and 262 were written.

In the years after the second Council of Constantinople in 553, both pro- and anti-Chalcedonians had occasionally spoken of Christ having a single activity (energeia), language which had some precedent in authors regarded as authoritative by both factions. But the validity of this so-called monoenergist doctrine was still very much a live issue on which there was no consensus in either pro- or anti-Chalcedonian circles. In the 610s, however, Sergius of Constantinople (patriarch 610–638) began to promote the doctrine of monoenergism in the name of Emperor Heraclius (r. 610–641) not only as a possible basis for reconciliation between the imperial church and miaphysite anti-Chalcedonians, but also as a legitimate clarification of Neo-Chalcedonian Christology. The apogee of imperially backed monoenergism came in 633 when on its basis Cyrus the Chalcedonian patriarch of Alexandria reached an accord with Egyptian miaphysites, an agreement memorialized in the Plerophoria, also known as the Pact of Union.

All that survives of the epistolary corpus of Apollinarius of Laodicea (ca. 315–392) are four intact letters and fragments of four others.1 What is probably the earliest Christological statement we have from Apollinarius is found in his Letter to Emperor Jovian, also called The Profession of Faith to Emperor Jovian, a letter to the new (pro-Nicene) emperor Jovian, who ascended to the throne in June 363 and ruled until his death in February 364. This letter might simply be an introductory statement of faith to a new emperor, which other bishops generally saw as unavoidable formalities to be completed without making waves. Indeed, Athanasius’s letter to Jovian (Ep. 56) simply repeated the Nicene Creed with little interpolation or interpretation. However, the fact that Apollinarius took the exercise as an opportunity to submit his Christological thought for imperial consideration might suggest a different context, perhaps that he was offering the new emperor a way forward in the efforts to reconcile the Christian factions in Antioch (Eustathians, Meletians, “Arians” of various stripes) by highlighting his own position.

Emperor Justinian reigned from 527 to 565, but had already played a decisive role in the reign of his uncle and predecessor Justin I (r. 518–527). Before Justin, imperial policy in Christological matters was officially dictated by the Henotikon that had been issued in 482 to reconcile pro- and anti-Chalcedonian factions within the church. Written by the patriarch Acacius of Constantinople and promulgated by Emperor Zeno, this document embraced a studied ambiguity by avoiding technical terminology in minimalist Christological formulations, by giving approval to both aspects of Cyril’s theology (represented by the strongly miaphysite Twelve Chapters and the dyophysite-leaning Letter of Reunion to John of Antioch), and by reducing the council’s work to the condemnation of Nestorius and Eutyches in order to undermine the achievement of the Chalcedonian Definition. Western bishops, who held Chalcedon in high regard, rejected the Henotikon outright, leading the bishop of Rome to break off communion with Acacius, resulting in the so-called Acacian Schism.

Ignatius, bishop of Antioch in Syria, penned seven letters while being escorted under guard to Rome for execution during the reign of Trajan (98–117 CE). No explicit evidence confirms that he reached the imperial capital, but there is no reason to doubt the tradition that he was martyred there. These letters illuminate numerous aspects of early Christian life and thought, providing as well insight into their author’s concerns. Since the seventeenth century these letters have been included in the collection of early Christian writings known as the Apostolic Fathers. Three matters above all repeatedly surface in these letters: (1) Ignatius’s struggle against those whose teaching differed from his own; (2) his pleas for the unity of the church by communion with and obedience to the bishop; and (3) his own suffering and impending death and their meaning, which he interprets in Christological categories.

Eusebius of Dorylaeum was a fifth-century bishop and a prominent theologian. Trained in legal practice, he became a distinguished rhetorician in Constantinople. His significant erudition earned him esteem at the imperial court. While still a layperson, Eusebius became the first person to contest Nestorius, the newly installed archbishop of Constantinople, in order to defend the title Theotokos for the Virgin Mary. When Nestorius challenged the theological propriety of the title, Eusebius confronted him in church. Cyril of Alexandria recounted the incident as follows:

The Council of Chalcedon affirmed that Leo’s Tome to Flavian of Constantinople was in harmony with the creeds of Nicaea and Constantinople and the conciliar letters of Cyril – but not without controversy. Some bishops criticized three passages in the Tome for emphasizing the duality of natures in Christ, which seemed to them to come alarmingly close to the “Nestorian” tendency to divide the natures in Christ so much that they acted and experienced independently of each other. These objections were eventually resolved at Chalcedon, enabling the bishops to acclaim the Tome as a definition of orthodoxy and to commend it in the Definition of Faith they produced as a “confirmation of right doctrines.” But those opposed to the decisions of Chalcedon continued to regard Leo’s Tome to Flavian as tainted by “Nestorianism.”

Eutyches (ca. 378–454) became a polarizing figure in the post-Cyrillian Christological debates leading up to the Council of Chalcedon in 451. A monk since his youth, Eutyches was eventually ordained a presbyter and around 410 became an archimandrite of a monastery outside the walls of Constantinople. At the Council of Ephesus in 431 he emerged as part of Cyril of Alexandria’s circle of supporters and a fierce opponent of Nestorius. Unexpectedly, however, on November 8, 448, when the Home Synod of Constantinople was in session, presided over by Archbishop Flavian, Bishop Eusebius of Dorylaeum accused Eutyches of heresy. The proceedings against the archimandrite were conducted over the course of seven sessions, concluding with his deposition on November 22. The acts of this synod offer a rare glimpse into the debate over Eutyches, allowing the reader to observe the bishops and Eutyches in action as the former prosecute their case and the latter attempts to thwart their efforts. The acts also are a precious record of the archimandrite’s views, which are difficult to reconstruct because his extant writings are few, short, and theologically sparse.

In the uproar in the moments immediately after Eutyches was excommunicated at the Home Synod of Constantinople on November 22, 448, the disgraced archimandrite tried to appeal to a council of the bishops of Rome, Alexandria, Jerusalem, and Thessalonica. His request was ignored, but soon after the synod, likely within weeks of it ending, Eutyches wrote letters to the bishops of these major sees making the same request. In his letter to Pope Leo of Rome – which alone survives of all those sent to the bishops, though they must have been very similar – Eutyches gives a fascinating account of the Home Synod from his perspective. Unsurprisingly, he depicts Flavian as corrupt and himself as the victim of a conspiracy to destroy him. His basic narrative does not deviate significantly from the sequence of events found in the acts of the seventh session of the Home Synod, but Eutyches gives further details and even mentions a few things that were not recorded in the official acts. For example, we learn that he had prepared a statement to read when he first appeared at his trial, which he calls a “profession of faith,” but Flavian disallowed it.