Alexandria has a long history of producing intellectual giants so it is no surprise to find St. Cyril of Alexandria exercising such a great influence over the Christian world of the 5th century, and even further after his death into the 6th century and beyond. His work On the Unity of Christ addresses Nestorianism primarily (which he considers a sort of “twin” to Arianism, p.51), but occasionally argues against Apollonarianism as well. Nestorius (historically understood) taught that a perfect man was “conjoined” to the eternal Son, the Word of the Father, but was not “united” with him. The flesh was that of a “son of David” and was not the Son’s own. In contrast, Cyril argues for orthodoxy insisting from scripture that it was the Son’s own flesh which suffered and died. If it were not, how could our nature be healed? If the flesh were only that of a “son of David” then he receives life as a gift and having received it may not give it to others. Only if the Man Jesus has life himself as his very own may he pass it to others and so redeem our corrupt nature. He says, “[T]here was no other way to shake off the gloomy Dominion of death, only by the incarnation of the Only Begotten. This was why he appeared as we are and made his own a body subject to corruption according to the inherent system of its nature. In so far as he himself is life, for he was born from the life of the Father, he intended to implant his own benefit within it, that is life itself" (125). Since this union is real, and the flesh is God's own (not merely adopted from a separate "son of David") it is right to call Mary Theotokos, God-bearer, or Mother of God. Nestorius refused her this title, calling her only "Mother of Christ." St. Cyril also address the doctrine of Apollonaris who denied that Jesus had a rational soul. He taught instead that the eternal Word replaced in Jesus what would be the soul in any other man. This must be rejected, Cyril says, because otherwise he is not "in all points like as we are." For Man is not wounded merely in the flesh but also in his rational soul and what Jesus "has not assumed he has not healed" (cf. Gregory Nazianzus).  In this work there is an obvious emphasis on the incarnation which is often lost in the West. Frequently redemption and atonement are narrowed to the cross. The incarnation is not seen as having any redemptive effect except insofar as it is the necessary condition which makes his redeeming death possible. But according to Cyril redemption is "by means of" the incarnation. This is the way we are granted theosis, or deification. This is the great reversal. "God became Man that Man may become god." Or as Cyril put it, "He Who Is, The One Who Exists, is necessarily born of the flesh, taking all that is ours into himself so that all that is born of the flesh, that is us corruptible and perishing beings, might rest in him. In short, he took what was ours to be his very own so that we might have all that is his" (59).