Both solutions offered perfectly logical deductions from the postulates assumed and it only wanted the advocates of one or the other to over-state the case so as to transgress against the teachings of philosophy or of traditional religion. The first false move came from Antioch. Laying great stress on the completeness of the humanity of Christ so that body, soul, and spirit were necessarily connected in the human frame, the view was so expressed as to describe the Virgin Mary as the mother of the human Christ, body, soul, and spirit alone, which implied, or seemed to imply, that at birth Christ was man only and afterwards became God by the Logos entering into the human body, a conclusion possibly not intended by those who expressed their views but pressed by their opponents. This had been the teaching of Diodorus and of Theodore of Mopseustia both associated with the school of Antioch, and defended in its extremer form by Nestorius, a monk of Antioch, who was made bishop of Constantinople in A.D. 428. Violent controversies ensued which resulted in a general council at Ephesus in 431, where the Alexandrian party succeeded in getting Nestorius and his followers condemned as heretics. Two years later the Nestorians, absolutely confident that their opponents were utterly illogical in supposing that the rational soul and the Logos in Christ were fused or united together, repudiated the official church and organised themselves as the Church which had no part with the heretics of Ephesus. The state Church, however, had the weight of the temporal authority behind it, and the heavy hand of persecution fell severely upon the Nestorians. In Antioch and Greek speaking Syria persecution did its work effectually and the Nestorians were reduced to the position of a fugitive sect, in Egypt, as might be expected, they had no footing, and the westerns as usual agreed with the dominant state church: only amongst the Syriac speaking Christians the Nestorian teaching had a free course, and that section for the most part adhered to it.
Some time before this the school at Nisibis had been closed, or rather removed to Edessa. In A.D. 363 the city of Nisibis had been handed over to the Persians as one of the conditions of the peace which closed the unfortunate war commenced by Julian, and the members of the school, retiring into Christian territory, had re-assembled at Edessa, where a school was opened in 373, and thus Edessa in a Syriac speaking district but within the Byzantine Empire, became the centre of the vernacular speaking Syriac church.
At the Nestorian schism the school at Edessa was the rallying place of those who did not accept the decisions of Ephesus, but in 439 it was closed by the Emperor Zeno on account of its strong Nestorian character, and the ejected members led by Barsuma, a pupil of Ibas (d. 457), who had been the great luminary of Edessa, migrated across the Persian border. Barsuma was able to persuade the Persian king Piruz that the orthodox, that is to say the state, Church was pro-Greek, but that the Nestorians were entirely alienated from the Byzantine Empire by the harsh treatment they had received. On this understanding they were favourably received and remained loyal to the Persian monarchy in the subsequent wars with the Empire. The Nestorians re-opened the school at Nisibis and this became the focus of Nestorian activity by which an orientalised phase of Christianity was produced. Gradually the Nestorian missionaries spread through all central Asia and down into Arabia so that the races outside the Greek Empire came to know Christianity first in a Nestorian form. It seems probable that Muhammad had contact with Nestorian teachers (Hirschfeld: New Researches. p. 23), and certainly Nestorian monks and missionaries had much intercourse with the earlier Muslims. These Nestorians were not only anxious to teach Christianity but very naturally attached the utmost importance to their own explanations of the person of Christ. This could only be made clear by the help of theories drawn from Greek philosophy, and so every Nestorian missionary became to some extent a propagandist of that philosophy: they translated into Syriac not only the great theologians such as Theodore of Mopseustia who explained their views, but also Greek authorities such as Aristotle and his commentators because some knowledge of these was necessary to understand the theology. Much of this work of translation shows a real desire to explain their teaching, but it shows also a strong resentment against the Emperor and his state church; as that church used the Greek language in its liturgy and teaching, the Nestorians were anxious to discard Greek, they celebrated the sacraments only in Syriac and set themselves to promote a distinctly native theology and philosophy by means of translated material and Syriac commentaries. These became the medium by which Aristotle and the neo-Platonic commentators were transmitted to Asia outside the Empire, and so later on as we shall see it was a group of Nestorian translators who, by making Arabic versions from the Syriac, first brought Hellenistic philosophy to the Arabic world. But there was also a weak side, for the Nestorian Church, cut off from the wider life of Hellenism, became distinctly provincial. Its philosophy plays round and round that prevalent at the schism, it spreads this philosophy to new countries, it produces an extensive educational system, and elaborates its material, but it shows no development. If we regard the main test of educational efficiency as being in its research product and not simply the promulgation of material already attained, then Nestorianism was not an educational success: and it seems that this should be the supreme test, for knowledge is progressive, and so the smallest contribution towards further progress must be of more real value than the most efficient teaching of results already achieved. Yet it would be difficult to over-estimate the importance of Nestorianism in preparing an oriental version of Hellenistic culture in the pre-Muslim world. Its main importance lies in its being preparatory to Islam which brought forward Arabic as a cosmopolitan medium for the interchange of thought and so enabled the Syriac material to be used in a wider and more fruitful field.
Although Nestorius had been condemned, the Church was left with a problem. The objection was true that, if the Logos and the rational soul in Christ were fused together so that the rational soul or spirit lost itself in its source, the Logos dwelt in an animal body and the full humanity of Christ disappeared. The Nestorian view of a temporary “connection” was now condemned as heretical, but was it necessary to go to the other extreme of “fusion” which was the logical result of the Alexandrian teaching? The Church wished to be philosophically correct and yet to avoid the conclusions which might be drawn from either view in its extreme form. In fact philosophy ruthlessly pressed home was the danger of which the Church was most afraid, feeling in some dim realm of sub-consciousness that the deposit of faith did not quite fall into line with science, or at least with the science then in fashion; and the Church’s real enemies were the enthusiasts who were confident that doctrine and philosophy were both absolutely true. Nor have we, even in these days, altogether learned the lesson that both are still partial and progressive. Islam had to go through exactly the same experience in her day and came out of it with very similar results, that is to say both the Christian and Muslim churches finally chose the via media adopting the philosophical statement of doctrine but condemning as heretical the logical conclusions which might be deduced. The Alexandrian school, elated perhaps at its victory over Nestorius, became rather intemperate in the statement of its views and pressed them home to an extreme conclusion. At once the warning prediction of the Nestorians was justified: the teaching of a “fusion” between the Logos and the rational soul in Christ entirely undermined his humanity. Another controversy ensued and in this, as in the former one, neither side suggested any doubt as to the psychology or metaphysics borrowed from the Aristotelian and neo-Platonic philosophies, that was throughout assumed as certain, the problem was to make Christian doctrine fit in with it. Now those who opposed the Alexandrian conclusions maintained the theory of a “union” between the Logos and the rational soul in Christ, so that the complete humanity was preserved as well as the deity, and the union was such as to be inseparable and so safeguarded from the Nestorian theory. In fact this was simply admitting the philosophical statement and forbidding its being pressed home to its possible conclusions. This is described as “orthodox” doctrine and rightly so in the sense that it expresses, though in philosophical terms, a doctrine as it was held before the Church had learned any philosophy, and excluded possible deductions which came within range as soon as a philosophical statement was made. This is the normal result when doctrine originally expressed by those ignorant of philosophy has to be put into logical and scientific terms: the only orthodox representation of the traditional belief must be a compromise.
This second controversy resulted in the Council of Chalcedon in A.D. 448, at which the advocates of the theory of “fusion” were expelled from the state church, and thus a third body was formed, each of the three claiming to represent the true faith. Practically the whole of the Egyptian Church followed the “fusionists” or Monophysites or Jacobites, as they were called after Jacob of Serugh, who was mainly instrumental in organizing them as a church: in Syria also they had a strong following. Like the Nestorians they were persecuted by the Emperor and the state church, but unlike them they did not migrate outside the Byzantine Empire, but remained an important though strongly disaffected body within its limits, though later on they sent out off-shoots into other lands. Like the Nestorians they tended to discard the language of their persecutors and to use the vernacular Coptic and Syriac: it is rightly claimed that the golden age of Syriac literature and philosophy begins with the Monophysite schism. A curious line of demarcation however, is observed in Syriac between the Jacobites in the West and the Nestorians in the East: they used different dialects, which is probably the result of their geographical distribution, and they used different scripts in writing which was partly due to deliberate intension, though partly also to the use of slightly different implements for writing.
When we consider the results of the Monophysite and Nestorian schisms we begin to understand why so much Greek philosophical material was translated into Syriac, whilst the Nestorian movement was the effective reason why Syriac gradually became the medium for transmitting Hellenistic culture into the parts of Asia which lay beyond the confines of the Byzantine Empire during the centuries immediately preceding the outspread of Islam. It is obvious that the late Aristotelian and neo-Platonic philosophers were of vital importance to everyone engaged in the theological controversies of the day, and the Aristotelian logic was of equal importance as on it depended the way in which terms were used. After their separation from the Greek Church the Nestorians and Monophysites turned to the vernacular speaking Christians, and so a large body of philosophical as well as theological matter was translated into Syriac; very much less into Coptic, for the Egyptian Monophysites were not called upon to face so much controversy as their brethren in Syria.
The period between the schisms and the beginning of Muslim interest in philosophy was one of prolific translation, commenting, and exposition. Whilst there is much interest in tracing the literary history of a nation, there is comparatively little in following the history of a literature which is confined to activities of this sort, for it cannot be much more than a list of names. Commentary and essay might indeed open up a field of originality, but nothing of the sort appears in this type of Syriac work: it seems as though the provincialism which followed severance from the Greek world brought in narrowing restrictions so that, although we get able and diligent workers, they never seem able to advance beyond re-statement, more or less accurate, of results already achieved.
Besides philosophy and theology we find a considerable interest in medicine and the two sciences of chemistry and astronomy which were treated as allied to it, for astronomy, regarded from the astrological point of view, was supposed to be closely associated with the conditions of life and death, of health and disease. Medical studies were especially attached to the school of Alexandria. Philosophy proper had been so largely taken over by theology that the secular investigators were rather impelled to turn to the natural sciences and as a centre of medical and allied studies the ancient school of Alexandria continued its development without loss of continuity, but under changed conditions. John Philoponus, or John the Grammarian, as he was called, was one of the later commentators on Aristotle and also one of the early lights of this medical school. The date of his death is not known, but he was teaching at Alexandria at the time when Justinian closed the schools at Athens in A.D. 529. The next great leader of this school was Paul of Aegina who flourished at the time of the Muslim conquest, and whose works long served as popular manuals of medicine. The founders of the medical school at Alexandria established a regular course of education for the training of medical practitioners, and for this purpose selected sixteen works of Galen, some of which were re-edited in an abridged form, and were made the subject of regular explanatory lectures. At the same time the school became a centre of original research, not only in medicine, but also in chemistry and other branches of natural science. Thus, on the eve of the Muslim conquest Alexandria had become a great home of scientific enquiry. To some extent this was unfortunate as the existing traditions in Egypt directed those investigations very much into obscurantist lines and tended to the use of magical forms, talismans, etc., and to introduce an astrological bias. This afterwards became the great defect of Arabic medicine as appears later even in mediæval Padua, but it was not the fault of Islam, it was an inheritance from Alexandria. Such material as remains of Syriac research shows us a saner and sounder method in vogue there, but Alexandria had eclipsed the Syrian scientists at the time of the Muslim invasion, at least in popular esteem, and this was a determining factor in directing Arabic research into these astrological by-paths.
Amongst the famous products of this school was Paul of Aegina, whose medical works formed the basis of much of the mediæval Arabic and Latin teaching, and the priest Ahrun (Aaron) who composed a manual of medicine which was afterwards translated into Syriac and became a popular authority. Alexandria was the centre also of chemical science, and as such was the parent of later Arabic alchemy. It appears from M. Berthelot’s exhaustive study of Arabic chemistry (La chimie au moyen age: Paris, 1893) that the Arabic material may be divided into two classes, the one based upon, and mainly translated from, the Greek writers current in Alexandria, the other representing a later school of independent investigation. Of the former class Berthelot gives three specimens, the Books of Crates, of al-Habid, and of Ostanes, all representing the Greek tradition which flourished at Alexandria on the eve of the Muslim invasion.