Imagination & Interpretation:
Recapitulation is an interpretive method that takes its starting point in the climactic Christological or salvation historical events. Irenaeus sees Christ as recapitulating all of human history...
This principle of recapitulation means that for Irenaeus the proper way to read the Old Testament is with the question in mind: how does this passage speak about Christ? Some Old Testament passages do this, of course, by means of prophetic messianic announcement, so that the reader can discern a prophecy-fulfillment schema. But the Old Testament narratives generally do not have such a plainly intended future reference to Christ. Irenaeus nonetheless insists that also such narratives have reference to Christ. For instance, by means of the tenth plague, God "saved the children of Israel, showing forth in a mystery the Passion of Christ, by the immolation of a spotless lamb, and by its blood, given as a guarantee of immunity to be smeared on the houses of the Hebrews" (Irenaeus, Proof of the Apostolic Preaching). Christ "was sold with Joseph, and He guided Abraham; was bound along with Isaac, and wandered with Jacob; with Moses He was a Leader, and, respecting the people, Legislator. He preached in the prophets...." (Irenaeus, Fragments from the Lost Writings of Irenaeus).
When Irenaeus insists on Christ's presence in the Old Testament narratives, he does not mean that there is no difference between Old and New Testament. Quite the contrary!....the salvific events of the new covenant are climactic in the absolute sense of the term. Instead, what Irenaeus does by locating Christ in the Old Testament is to acknowledge the interpretive significance of Christ for the Old Testament. With the coming of Christ, it is no longer possible to regard the historical events of the Old Testament as simply that. The incarnation has embedded a deeper level of interpretation into the Old Testament narratives. Christ has now become the only proper interpretive lens for reading the Old Testament.
- Hans Boersma, Imagination & Interpretation: Christian Perspectives, p. 22-23, emphasis mine