From my other blog, Wisdom!: Readings from the Fathers of the Church:
The mystery hidden from the ages (Col 1:26) and from the nations is now revealed through the true and perfect incarnation of the Son and God. For he united our nature to himself in a single hypostasis, without division and without confusion, and joined us to himself as a kind of first fruits. This holy flesh with its intellectual and rational soul came from us and is ours. He deemed us worthy to be one and the same with himself according to his humanity. For we were predestined before the ages (cf Eph 1:11-12) to be in him as members of his body. He adapted us to himself and knitted us together in the Spirit as a soul to a body and brought us to the measure of spiritual maturity derived from his fullness. For this we were created; this was God’s good purpose for us before the ages. But this renewal did not come about through the normal course of things, it was only realized when a wholly new way of being human appeared. God had made us like himself and allowed us to participate in the very things that are most characteristic of his goodness. Before the ages he had intended that man’s end was to live in him, and to reach this blessed end he bestowed on us the good gift of our natural powers. But by misusing our natural powers we willingly rejected the way God had provided and we became estranged from God. For this reason another way was introduced, more marvelous and more befitting of God than the first, and as different from the former as what is above nature is different from what is according to nature. And this, as we all believe, is the mystery of the mystical sojourn of God with men. For if, says the divine apostle, the first covenant had been blameless, there would have been no occasion for a second (Heb 8:7). It is clear to all that the mystery accomplished in Christ at the end of the age (Heb 9:26) shows indisputably that the sin of our forefather Adam at the beginning of the age has run its course.
(in Paul M. Blowers and Robert Louis Wilken, trs., On the Cosmic Mystery of Jesus Christ, pp 70-71)