There are so many historical details to manage in the study of the NT and OT canon, that it is often difficult to step back and get the big picture. Scholarly energies are typically preoccupied with whether a certain church father cited a certain biblical book, and thus the entire biblical collection is rarely viewed as a completed whole.
In short, we tend to study the canon one book at a time. But, as Walter Brueggemann observed regarding this approach, “That is problematic because one never gets a sense of the whole of the Bible” (Creative Word, 5).
When we take that step back, and examine the overall canonical structure, some fascinating details emerge. One noteworthy example is the fact that the complete biblical canon can be viewed in seven distinct units.
There are good historical reasons to think that the OT canon in the time of Jesus was divided into the standard tripartite structure: the Law, the Prophets, and the Writings. The structure finds confirmation in a number of historical sources that we cannot examine fully here (b. Bat. 14b; Josephus, Ap. 1.37-42; 4QMMT (95-96); Philo, Contempl. Life, 25. ). Jesus even seems to allude to this tripartite structure when he says, “Everything written about me in the Law of Moses, and the Prophets, and the Psalms must be fulfilled” (Luke 24:44).
When it comes to the structure of the NT canon, at least as it emerged within the early church, it seems to have been divided into four sections. David Trobisch has demonstrated that these four clear sub-sections—Gospels, Praxapostolos (Acts and Catholic epistles), Pauline epistles, and Revelation—as can be seen from the uniform witness of the manuscript collections themselves (The First Edition of the New Testament).
Thus, when the OT and NT canons are considered together, it seems the overall biblical canon would have had a seven-fold structure. Given the well-established biblical usage of the number seven as representative of completeness or wholeness, a seven-fold canonical structure would speak to the overall unity of the biblical canon and provides further reason to think that the New Testament canon we possess is the proper conclusion to the original books of the Old Testament.
Moreover, a structure that has Genesis and Revelation as the “bookends” is particularly fitting given the role the number seven plays in each of those books. Genesis begins the biblical witness with a seven-fold creative structure that provides the foundation for the seven-fold work week, and then Revelation recapitulates this attention to the number seven by having seven churches, seven angels, seven seals, seven trumpets, seven bowls, seven plagues, and so on.
Thus, in effect, the first and last books of the canon form an “inclusio” of sevens, functioning as appropriate bookends to the overall seven-fold canonical structure—with Revelation as an appropriate “sabbath.”
Of course, many of these connections are only apparent when we view the canon as a whole and therefore would not have been as accessible to the earliest Christians who did not yet possess a completed canon (or had the books in a different order, as some did). This fact reminds us again that some qualities of canonicity are synergistic—the whole can be greater than the constituent parts. It is like the “fifth voice” of a barbershop quartet; you only hear it when all four voices are joined together in harmony.
In the end, the canon’s seven-fold structure fits with the kind of structure we might expect God to give to his revelation, namely a structure that attests to the harmony, coherence, and unity of his Word.