The Incarnation, Cyril maintains, has not involved any change in respect of the divine being of the Logos. The Logos, he constantly affirms, “remains what He was”. If we interpret him aright, his view is that the Logos, who, “being true God, is never external to his own dignity”, has “added” to His eternal being this—that He has undergone “a voluntary self-emptying” through becoming man for man’s salvation. Thus we find that he says that the Logos, while existing eternally in the form of the Father, “besides this” (πρός γε τούτῳ) took the form of a servant, that He counted it not a prize to be on an equality with God, but “besides this” (προσέτι τούτῳ) took the form of a servant—which he had not done before—though possessing the fullness (of Godhead) in His own nature. Again it should be noted that he can say the Same, remaining what He was, and becoming what we are, manifested an activity which was twofold (διπλῆν τὴν ἐνέγειαν)—”suffering as man and energising God”. Even if it is not developed, this would appear to be a workable idea.
We must notice, too, that Cyril, building upon the principle that “Incarnation is self-emptying”, carries forward the thought of his predecessors, who had realised that their system demanded the inclusion of the conception that in the Incarnation the Logos has accommodated Himself to earthly conditions. While for him, as for all the teachers of the Alexandrine school, the Incarnation is a supreme mystery, he sees that the self-emptying of the Logos, who in His divine being cannot suffer any change, is to do and to say what is human through the economic union with the flesh. To separate Him from what is human, he argues against the Antiochenes, is to overturn the whole mystery. So he asserts that the Logos “went through the laws of human nature.” But he perceives that a real incarnation is only possible if the Logos limits Himself in respect of His divine powers. Hence, with Athanasius, he can say that the Logos “allowed” the humanity to fulfil its own measures. But this is not all. Especially significant in this connection is the following remark of his: the Logos, he says, might have taken the Babe out of the swaddling clothes and lifted Him (at once) to the fulness of manhood, but this would have been mere wonder-working, and out of harmony with the conditions of the economy; rather—
the mystery was accomplished noiselessly. Therefore, in accordance with the economy, He permitted the measures of the manhood to prevail over Himself (ἠφίει δὴ οὖν οἰκονομικῶς τοἴς τῆς ἀνθρωπότητος μέτροις ἐφ᾽ἑαυτῷ τὸ κρατεἴν)
Here again we have an important contribution to the Christological thought, and even if it has to be confessed—and to this point we shall return—that Cyril “restricts the reign of the law to the material sphere, excluding it from the intellectual and moral”, it stands as a sound principle, and one which can be developed: the Logos, while still remaining the Creative Word, assumes manhood, and in so doing, subjects Himself to human laws.