CCC 359 “In reality it is only in the mystery of the Word made flesh that the mystery of man truly becomes clear.”1
St. Paul tells us that the human race takes its origin from two men: Adam and Christ. .. The first man, Adam, he says, became a living soul, the last Adam a life-giving spirit. The first Adam was made by the last Adam, from whom he also received his soul, to give him life. .. The second Adam stamped his image on the first Adam when he created him. That is why he took on himself the role and the name of the first Adam, in order that he might not lose what he had made in his own image. The first Adam, the last Adam: the first had a beginning, the last knows no end. The last Adam is indeed the first; as he himself says: “I am the first and the last.”2
1 GS 22 # 1.
2 St. Peter Chrysologus, Sermo 117: PL 52, 520-521.