Schaff, Philip. History of the Christian Church (The Complete Eight Volumes in One). Amazon Kindle Edition, 2014.
Volume 2, Ante-Nicene Christianity A.D. 100-325, “Chapter 12. The Development of Catholic Theology in Conflict with Heresy” Sections 137-158, Loc. 18758-20235.
§ 147. The Relation of the Divine and the Human in Christ.
Schaff considers that the discussion of the two natures in Christ and their relationship was not at a head until the fifth century. However, the idea is present in Irenaeus, who “teaches unequivocally a true and indissoluble union of divinity and humanity in Christ” counter to the Gnostics (Schaff 2014, Loc. 19504). He finds in general that the divine nature shows primarily in creation and the human nature in his receptive nature on earth. The two natures he sees bound together by the Holy Spirit, who overshadowed Mary. Irenaeus further sees Jesus as the second Adam and Mary, in a sense, as the second Eve, mother of all righteousness (Schaff 2014, Loc. 19511).The idea of Jesus as “God-man” comes from Origen, also the first to use the metaphor of iron warmed in a fire taking on the nature of the fire (Schaff 2014, Loc. 19517).