The commentator at the beginning of the fifth century had therefore a long tradition behind him, especially in the interpretation of the great Christological texts of the Gospel. The primary feature of that tradition was the clear differentiation between those things which referred to Christ's manhood and those which referred to his Godhead. In the third century, it was the demonstration of the existence of these two sets of sayings which had provided an answer to the psilanthropist on the one hand and the docetist on the other, both of whose cases had been founded on an incomplete selection of the relevant evidence. In the fourth century, it was the drawing of a clear distinction between the two sets of sayings which had provided an answer to the Arian, who had combined them in such a way as to produce the picture of one who was neither fully God nor fully man. By the beginning of the fifth century, however, Arianism was no longer the primary issue. It was sufficiently recent, and no doubt also still sufficiently common in popular belief, to ensure that there would be no wholesale abandonment of those techniques which had proved of most importance in countering it. But a new issue had arisen to fill the immediate horizon—namely the manner of the combination of the divine and human in the one Christ.

This also was an issue for which the interpretation of the Fourth Gospel was of especial significance. Long before, Irenaeus had claimed that the Gospel was deliberately designed to refute the blasphemous teachings of those who divided the Lord.