The introductions to the books of Genesis and Revelation are underlain by similar grammatico-numerical patterns.
Genesis
The first three verses of the book of Genesis introduce us to three creative agents:
the God who is the primary mover behind Genesis 1.1–2.3’s events,
the Spirit/Breath of God who hovers above the waters, ready to act, and
the spoken/breathed-out Word, by means of which God creates.
Then, as Creation unfolds, a host of allusions to the numbers three and seven emerge. God creates over the course of a seven-day period, made up of two three-day panels and crowned with a Sabbath. On Days One to Three God creates a three-tier world—sky, land, and sea—, and on the next three days he fills it with three created trios (the greater light, lesser light, and stars; sea-serpents, other sea-creatures, and birds; and beasts, livestock, and reptiles: 1.16, 21, 25). The text’s first two verses (a literary ‘Day Zero’) consist of 21 words (3 x 7). God’s actions on Day Seven are described by means of 21 words, which break down into three seven-word sentences (Gen. 2.2–2.3a). And the focal point of the God of Heaven’s activities—viz. ‘the earth’—is mentioned exactly 21 times.
Revelation
As Peter Leithart notes in his commentary, the start of the book of Revelation is replete with similar threefold and sevenfold patterns.
First of all we have a threefold chain of transmission (God to Jesus, Jesus to his angel, and his angel to John) followed by a threefold promise (to those who read, hear, and keep).
Next we have references to the three persons of the Trinity, in the same (unexpected) order as they occur in Genesis 1. Specifically, we have references to:
the Father, who is described via a threefold title (as he who is, who was, and who is to come),
the sevenfold Spirit stationed before the throne, ready to serve, and
the incarnate sent-forth Word, who also has a threefold title, viz. he who is the faithful witness, the firstborn from the dead, and the ruler of the kings of the earth.
Thereafter, the book of Revelation describes six sevenfold strands of world history—the lives/effects of the seven churches, seals, trumpets, thunders, kings, and plagues—, which culminate in the return of Christ and the inauguration of a Sabbath-like new creation (Rev. 21–22).
Hence, just as Jesus arrives at the start of the NT at the climax of six heptads (three fourteens, per Matthew’s genealogy), so he arrives at the climax of six heptads at the end of the NT (as well as at the climax of a period of 42 months).
Significance
These and other parallels between Genesis 1 and Revelation are, of course, no coincidence. Revelation is all about the de-creation of an old world and the rise of a new one in its place. And, as the book progresses, God’s people are brought into that new creation’s goodness. They are granted to eat from the tree of life, not to be hurt by the second death, and to share in the joys outlined at the close of Revelation 7 (Leithart 2018:343).
I really like the observation about the six heptads in both Matthew and Revelation!
Really interesting. One thing I've wondered is in Rev.20 there are 6 "one thousand years". I always thought we'd be a expecting a 7th.