"he who existed and was begotten of the Father before all ages is also said to have been begotten according to the flesh of a woman, without the divine nature either beginning to [(42)] exist in the holy virgin, or needing of itself a second begetting after that from his Father. . . . The Word is said to have been begotten of the flesh, because for us and for our salvation he united what was human to himself hypostatically and came forth from a woman. For he was not first begotten of the holy virgin, a man like us, and then the Word descended upon him; but from the very womb of his mother he was so united and then underwent begetting according to the flesh, making his own the begetting of his own flesh. . . ."
 "the only-begotten Word of God, who was begotten from the very essence of the Father, true God from true God, the light from the light and the one through whom all things in heaven and [(51)] earth were made, for our salvation came down and emptying himself he became incarnate and was made man. This means that he took our flesh from the holy virgin and made it his own, undergoing a birth like ours from her womb and coming forth a man from a woman. He did not cast aside what he was, but although he assumed flesh and blood, he remained what he was, God in nature and truth. . . . For although visible as a child and in swaddling cloths, even while he was in the bosom of the virgin that bore him, as God he filled the whole of creation and was fellow ruler with him who begot him. . . ."
 "Therefore, because the holy virgin bore in the flesh God who was united hypostatically with the flesh, for that reason we call her mother of God [(θεοτόκον, Dei genetricem)], not as though the nature of the Word had the beginning of its existence from the flesh (for 'the Word was in the beginning and the Word was God and the Word was with God', and he made the ages and is coeternal with the Father and craftsman of all things), but because, as we have said, he united to himself hypostatically the human and underwent a birth according to the flesh from her womb. This was not as though he needed necessarily or for his own nature a birth in time and in the last times of this age, but in order that he might bless the beginning of our existence, in order that seeing that it was a woman that had given birth to him, united to the flesh, the curse against the whole race should thereafter cease. . . ."
". . . What is [therefore] required for your reverence to anathematise we subjoin to this epistle.
"1. If anyone does not confess that Emmanuel is God in truth, and therefore that the holy virgin is the mother of God [(θεοτόκον, Dei genetricem)] (for she bore in a fleshly way the Word of God become flesh), let him be anathema."
Second and third letters of St. Cyril of Alexandria to Nestorius, as translated in Decrees of the ecumenical councils, ed. Norman P. Tanner, S.J., Volume one: Nicaea I to Lateran V (London: Sheed & Ward Limited; Washington D. C.: Georgetown University Press, 1990), 41-42, 50-51, 58, and 59.