For this purpose, then, the incorporeal and incorruptible and immaterial Word of God (tou θeoῦ Λὀγoς) comes into our realm, although He was not formerly distant. For no part of creation is left void of Him; while abiding with His own Father, He has filled all things in every place. But now He comes, condescending towards us in His love for human beings and His manifestation. For seeing the rational race perishing, and death reigning over them through corruption, and seeingf also the threat of the transgression giving firm hold to the corruption that was upon us, and that it was absurd for the law to be dissolved before being fulfilled, and seeing the impropriety in what had happened, that the very thing of which He Himself was the Creator were disappearing, and seeing the excessive wickedness of human beings, that they gradually increased it to an intolerable pitch against themselves, and seeing the liability of all human beings to death--having mercy upon our race, and having pity upon our weakness, and condescending to our corruption, and not enduring the dominion of death, least what had been created should perish and the work of the Father Himself for human beings should be in vain,He takes for Himself a body and that not foreign to our own.
For He did not wish simply to be in a body, nor did He wish merely to appear, for if He had wished only to appear He could have made His divine manifestation through some other better means. But He takes that which is ours, and that not simply, but from a spotless and stainless virgin, ignorant of man, pure and unmixed with intercourse with men. Although being Himself powerful and the creator of the universe, He prepared for Himself in the Virgin the body as a temple, and made it His own, as an instrument, making Himself known and dwelling in it. And thus taking from ours that which is like, since all were liable to the corruption of death, delivering it over to death on behalf of all, He offered it to the Father, doing this in His love for human beings, so that, on the one hand, with all dying in Him the law concerning corruption in human beings might be undone (its power being fully expended in the lordly body and no longer having any ground against similar human beings), and on the other hand, that as human beings ha d turned towards corruption He might turn them again to incorruptibility and give them life from death, by making the body His own and by the grace of the resurrection banishing death from them as straw from the fire.
St.Athanasius, "On the Incarnation" , (Translation by John Behr)