the true humanity of Christ, the next question was as to how the two elements could co-exist in one and the same Person. Thus the discussion moved from the question of the Trinity, which had occupied the thoughts of theologians of the fourth century, to the consideration of the nature of Christ, which was to engage the minds of disputants during the fifth century, and beyond into the sixth and even the seventh. The controversies became more and more hard and narrow, unspiritual and purely polemical, as the weary process went on, till the Church woke up with a rude shock in the advent of Mohammedanism, to face the vital question whether Christianity was to continue to exist at all—in any form, orthodox or heterodox. The two heresies which rent the Eastern Church during the fifth century scarcely touched the West, although the bishop of Rome intervened from time to time to help towards a settlement. Therefore they belong essentially to the Oriental branch of Church history. Moreover, their effects are seen in the divisions of Eastern Christendom in the present day, one of them being represented by the Nestorians of the Euphrates and India, the other by the Syrian Jacobites and the Copts in Egypt. In the controversies of the fifth century we see the rise of both the movements which have perpetuated themselves in these two groups of Christians out of communion with the Greek Church, both of them denounced by "the holy orthodox Church" as heretical.
We saw how the Christological speculations began to appear even during the course of the fourth century in those two very original thinkers, Apollinaris and Gregory of Nyssa.[1] The former had been condemned by the council of Constantinople for denying the full humanity of Christ; and the latter had come to be looked on with suspicion on account of his sympathies with the ideas of Origen. After this, whatever new lines of thought are followed had to come within those laid down in the Nicene and Constantinopolitan settlement. Still, within the limits thus decided there was room for considerable variety of
