In the Third Book of his tome Against Heresies, St. Irenaeus writes,
…Luke points out that the pedigree which traces the generation of our Lord back to Adam contains seventy-two generations, connecting the end with the beginning, and implying that it is He who has summed up in Himself all nations dispersed from Adam downwards, and all languages and generations of men, together with Adam himself. Hence also was Adam himself termed by Paul “the figure of Him that was to come,” because the Word, the Maker of all things, had formed beforehand for Himself the future dispensation of the human race, connected with the Son of God; God having predestined that the first man should be of an animal nature, with this view, that he might be saved by the spiritual One. For inasmuch as He had a pre-existence as a saving Being, it was necessary that what might be saved should also be called into existence, in order that the Being who saves should not exist in vain.
This is a rich and mysterious passage. Below, I will speculate that this selection teaches a variety of interesting doctrines, including the eternal generation of the Son (which some scholars think the Saint did not teach) and that the Incarnation would happen without the fall. I recommend Perry’s post Cur Deus Homo as pre-reading. For a short summary of my analysis below, skip to the Conclusion and Why This Matters. (more…)