St. Gregory the Theologian, Oration 38, Section 13:
The human being was first educated in many ways corresponding to the many sins that sprouted from the root of evil for different reasons and at different times; by word, law, prophets, benefits, threats, blows, floods, conflagrations, wars, victories, defeats; signs from heaven, signs from the air, from earth, from sea; unexpected changes in men, cities, nations; by all this God sought zealously to wipe out evil. At the end a stronger remedy was necessary for more dreadful diseases: murders of each other, adulteries, false oaths, lusts for men, and the last and first of all evils, idolatry and the transfer of worship from the Creator to creatures. Since these things required a greater help, they also obtained something greater. It was the Word of God himself, the one who is before the ages, the invisible, the ungraspable, the incorporeal, the Principle from the Principle, the light from the light, the source of life and immortality, the imprint of the archetypal beauty, the immutable seal, the undistorted image, the definition and explanation of his Father. He approaches his own image and bears flesh because of my flesh and mingles himself with a rational soul because of my soul, purifying like by like. And in all things he becomes a human being except sin. He was conceived by the Virgin, who was purified beforehand in both soul and flesh by the Spirit, for it was necessary that procreation be honored and that virginity be honored more. He comes forth, God with what he has assumed, one from two opposites, flesh and spirit, the one deifying and the other deified. O new mixture! O the Paradoxical blending! He who is comes into being, and the uncreated is created, and the unconfined is contained, through the intervention of the rational soul, which mediates between the divinity and the coarseness of flesh. The one who enriches becomes poor; he is made poor in my flesh, that I might be enriched through his divinity. The full one empties himself; for he empties himself of his own glory for a short time, that I may participate in his fullness. What is the wealth of his goodness? What is this mystery concerning me? I participated in the [divine] image, and I did not keep it; he participates in my flesh both to save the image and to make the flesh immortal. He shares with us a second communion, much more paradoxical than the first; then he gave us a share in what is superior, now he shares in what is inferior. This is more godlike than the first; this, to those who can understand, is more exalted.