I. The Nestorians:
Ebedjesu (Nestorian, d.1318): Liber Margarita de veritate fidei, in Angelo Mai's Script. veter. Nova Collectio, Vol. XII. p.317.
Jos. Sim. Assemani (R. C., d.1678): De Syris Nestorianis, in his Bibl. Or., Rom.1719-28, Tom. III. Pt. II.
Gibbon : Decline and Fall of the Roman Empire, chap, xlvii. near the end.
E. Smith and H. G. C. Dwight: Researches in Armenia, with a Visit to the Nestorian and Chaldean Christians of Oormiah, etc., 2 vols. Boston, 1833.
Justin Perkins: A Residence of Eight Years in Persia, Andover, 1843.
W. Etheridge : The Syrian Churches, their Early History, Liturgies, and Literature, Lond.1846.
Geo. Percy Badger: The Nestorians and their Rituals, Illustrated (with colored plates), 2 vols. Lond.1852.
H. Newcomb: A Cyclopædia of Missions, New York, 1856, p.553 sq.
Petermann: Article Nestorianer, Herzog's Theol. Encyklop. Vol. X. (1858), pp.279-288.
Rufus Anderson (late For. Sec. Am. Board of C. For. Missions: Republication of the Gospel in Bible Lands; History of the Missions of the Amer. Board of Comm. for For. Miss. to the Oriental Churches, Boston, 1872, 2 vols.
On the Nestorian controversy which gave rise to the Nestorian sect, see my Church History, Vol. III. p.715 sq., and the works quoted there; also p.729.
II. The Monophysites (Jacobites, Copts, Abyssinians, Armenians, Maronites):
Euseb. Renaudot (R. C., d.1720): Historia Patriarcharum Alexandrinorum Jacobitarum a D. Marco usque ad finem sæc. xiii., Par.1713. Also by the same: Liturgiarum Orientalium Collectio, Par.1716, 2 vols.4to.
Jos. Sim. Assemani (R. C.): Bibliotheca orientalis, Rom.1719 sqq., Tom. II., which treats De scriptoribus Syris Monophysitis.
Michael le Quien (R. C., d.1733): Oriens Christianus, Par.1740, 3 vols. folio (Vols. II. and III.).
Veyssière de la Croze: Histoire in Christianisme d'Ethiope et d'Armenie, La Haye, 1739.
Gibbon: Decline and Fall of the Roman Empire, chap, xlvii.
Makrîzi (Mohammedan, an historian and jurist at Cairo, died 1441): Historia Coptorum Christianorum (Arabic and Latin), ed. H. J. Wetzer, Sulzbach, 1828; a better edition by F. Wüstenfeld, with translation and annotations, Göttingen, 1845.
J. E. T. Wiltsch: Kirchliche Statistik, Berlin, 1846, Bd. I. p.225 sq.
John Mason Neale (Anglican): The Patriarchate of Alexandria, London, 1847, 2 vols. Also, A History of the Holy Eastern Church, London, 1850, 2 vols. (Vol. II. contains among other things the Armenian and Copto-Jacobite Liturgies.)
E. Dulaurier : Histoire, dogmes, traditions, et liturgie de l'église Armeniane, Par.1859.
Arthur Penrhyn Stanley: Lectures on the History of the Eastern Church, New York, 1862, p.92.
E. F. K. Fortescue: The Armenian Church. With Appendix by S. C. Malan, London, 1872.
Rufus Anderson: Republication of the Gospel in Bible Lands, quoted above.
Schaff: Church History, Vol. III. pp.334 sqq. and 770 sqq.
Compare accounts in numerous works of Eastern travel, and in missionary periodicals, especially the Missionary Herald, and the Annual Reports of the American Board of Foreign Missions.
Besides the Orthodox Greek Church there are scattered in the East, mostly under Mohammedan and Russian rule, ancient Christian sects, the Nestorians and Monophysites. They represent petrified chapters of Church history, but at the same time fruitful fields for Roman Catholic and Protestant Missions. They owe their origin to the Christological controversies of the fifth century, and perpetuate, the one the Nestorian, the other the Eutychian heresy, though no more as living issues, but as dead traditions. They show the tenacity of Christological error. The Nestorians protest against the third oecumenical Council (431), the Monophysites against the fourth (451). In these points of dispute the Latin and the orthodox Protestant Churches agree with the Orthodox Greek Church against the schismatics.
In other respects the Nestorians and Monophysites betray their Oriental character and original affinity with the Greek Church. They regard Scripture and tradition as co-ordinate sources of revelation and rules of faith. They accept the Nicene Creed without the Filioque; they have an episcopal and patriarchal hierarchy, and a ritualistic form of worship, only less developed than the orthodox. They use in their service their ancient native languages, although these have become obsolete and unintelligible to them, since they mostly speak now the Arabic. They honor pictures and relics of saints, but not to the same extent as the Greeks and Russians. The Bible is not forbidden, but practically almost unknown among the people. Their creeds are mostly contained in their liturgies.
They supported the Arabs and Turks in the overthrow of the Byzantine Empire, and in turn were variously favored by them, and upheld in their separation from the Orthodox Greek Church. They are sunk in ignorance and superstition, but, owing to their prejudice against the Greek Church, they are more accessible to Western influence.
Providence has preserved these Eastern sects, like the Jews, unchanged to this day, doubtless for wise purposes. They may prove entering wedges for the coming regeneration of the East and the conversion of the Mohammedans.
I. The Nestorians, in Turkey and Persia, are called after Nestorius, Patriarch of Constantinople. He was condemned by the Council of Ephesus, 431, for so teaching the doctrine of two natures in Christ as virtually to deny the unity of person, and for refusing to call Mary 'the Mother of God' (theotokos, Deipara), and he died in exile about 440. His followers call themselves Chaldæan or Syrian Christians. They flourished for several centuries, and spread far into Arabia, India, and even to China and Tartary. Mohammed is supposed to have derived his imperfect knowledge of Christianity from a Nestorian monk, Sergius. But by persecution, famine, war, and pestilence, they have been greatly reduced. The Thomas Christians of East India are a branch of them, and so called from the Apostle Thomas, who is supposed to have preached on the coast of Malabar.
The Nestorians hold fast to the dyophysite Christology of their master, and protest against the Council of Ephesus, for teaching virtually the Eutychian heresy, and unjustly condemning Nestorius. They can not conceive of a human nature without a human personality, and infer two independent hypostases from the existence of two natures in Christ. They object to the orthodox view, that it confounds the divine and human, or that it teaches a contradiction, viz., two natures and one person. The only alternative to them seems either two natures and two persons, or one person and one nature. From their Christology it follows that Mary was only the mother of the man Jesus. They therefore repudiate the worship of Mary as the Mother of God; also the use of images (though they retain the sign of the cross), the doctrine of purgatory (though they have prayers for the dead), and transubstantiation (though they hold the real presence of Christ in the eucharist); and they differ from the Greek Church by greater simplicity of worship. They are subject to a peculiar hierarchical organization, with eight orders, from the catholicus or patriarch to the sub-deacon and reader. The five lower orders, including the priests, may marry; in former times even the bishops, archbishops, and patriarchs had this privilege. Their fasts are numerous and strict. Their feast-days begin with sunset, as among the Jews. The patriarch and the bishops eat no flesh. The patriarch is chosen always from the same family; he is ordained by three metropolitans. The ecclesiastical books of the Nestorians are written in the Syriac language.
II. The Monophysites, taken together, outnumber the Nestorians, and are scattered over the mountains, villages, and deserts of Armenia, Syria, Egypt, and Abyssinia. They are divided into four distinct sects: the Jacobites in Syria; the Copts in Egypt, with their ecclesiastical descendants in Abyssinia;  the Armenians, and the ancient Maronites on Mount Lebanon (who were Monothelites, but have been mostly merged into the Roman Church).
The Armenians (numbering about three millions and a half) excel all the rest in numbers, intelligence, and enterprise, and are most accessible to Protestant missionaries.
The Monophysites have their name from their distinctive doctrine, that Christ had but one nature (mone phusis), which was condemned by the fourth oecumenical Council of Chalcedon. They are the antipodes of the Nestorians, whom they call Dyophysites. They agree with the Council of Ephesus (431) which condemned Nestorius, but reject the Council of Chalcedon (451). They differ, however, somewhat from the Eutychean heresy of an absorption of the human nature by the divine, as held by Eutyches (a monk of Constantinople, died after 451), and teach that Christ had one composite nature (mia phusis sunthetos or mia phusis ditte). They make the humanity of Christ a mere accident of the immutable divine substance. Their main argument against the orthodox or Chalcedonian Christology is that the doctrine of two natures necessarily leads to that of two persons, and thereby severs the one Christ into two sons of God. They regarded the nature as something common to all individuals of a species (koinon), yet as never existing simply as such, but only in individuals. Their liturgical shibboleth was, God has been crucified, which they introduced into the trisagion, and hence they were also called Theopaschites.
With the exception of the Chalcedonian Christology, the Monophysite sects hold most of the doctrines, institutions, and rites of the Orthodox Greek Church, but in simpler and less pronounced form. They reject, or at least do not recognize, the Filioque; they hold to the mass, or the eucharistic sacrifice, with a kind of transubstantiation; leavened bread in the Lord's Supper; baptismal regeneration by trine immersion; seven sacraments (yet not explicitly, since they either have no definite term for sacrament, or no settled conception of it); the patriarchal polity; monasticism; pilgrimages and fasting; the requisition of a single marriage for priests and deacons (bishops are not allowed to marry); the prohibition of the eating of blood or of things strangled. On the other hand, they know nothing of purgatory and indulgences, and have a simpler worship than the Greeks and Romans. According to their doctrine, all men after death go into Hades, a place alike without sorrow or joy; after the general judgment they enter into heaven, or are cast into hell; and meanwhile the intercessions and pious works of the living have an influence on the final destiny of the departed.
Note on Russian Schismatics. -- The dissenting sects of the Russo-Greek Church are very numerous, but not organized into separate communions like the older Oriental schismatics; the Russian government forbidding them freedom of public worship. They are private individuals or lay-communities, without churches and priests. They have no definite creeds, and differ from the national religion mostly on minor ceremonies. The most important among them are the Raskolniki (i.e. Separatists, Apostates), or, as they call themselves, the Starovers (Old Believers). They date from the time of Nicon, Patriarch of Moscow, and protest against the ritualistic innovations introduced by this remarkable man in the latter part of the seventeenth century, and afterwards by the Czar Peter the Great; they denounce the former as the false prophet, and the latter as the antichrist. They reject the benediction with three fingers instead of two, the pronouncing of the name of Jesus with two syllables instead of three, processions from right to left instead of the opposite course, the use of modern Russ in the service-books, the new mode of chanting, the use of Western pictures, the modern practice of shaving (unknown to the patriarchs, the apostles, and holy fathers), the use of tobacco (though not of whisky), and, till quite recently, also the eating of the potato (as the supposed apple of the devil, the forbidden fruit of paradise). They are again divided into several parties.
For information about these and other Russian Non-conformists, see Strahl: History of Heresies and Schisms in the Greek-Russian Church, and his Contributions to Russian Church History (I.250 sqq.); Hepworth Dixon: Free Russia (1870), and the literature mentioned in Herzog's Encyklop., Art. Raskolniken, Vol. XII. p.533.
 The Abyssinian Church receives its Patriarch (Abuna. i.e. Our Father) from the Copts, but retains some peculiar customs, and presents a strange mixture of Christianity with superstition and barbarism. See my Church History, Vol. III. p. 778.