Is there a significance for having 5 books, or is it just a coincidence?

[Joseph D. L.]

Irenaeus's Against Heresies was divided into five books; Tertullian's Against Marcion too. What's known of Papias's and Hegeippus's lost histories is that both were compiled into five books. And according to at least one ancient witness that I'm aware of, the original title for the Diatessaron (Of the Four) was Diapente, The Five. Of course the Torah itself is divided into five distinct yet consecutive books. Was there a greater intent here or is this just more of my paranoia?

[Ben C. Smith]

Irenaeus's Against Heresies was divided into five books; Tertullian's Against Marcion too. What's known of Papias's and Hegeippus's lost histories is that both were compiled into five books. And according to at least one ancient witness that I'm aware of, the original title for the Diatessaron (Of the Four) was Diapente, The Five. Of course the Torah itself is divided into five distinct yet consecutive books. Was there a greater intent here or is this just more of my paranoia?

Off the top of my head, add the Theophany by Eusebius and the Excidio by pseudo-Hegesippus to the list. (ETA: Full title of the latter: De Excidio Urbis Hierosolymitanae.)

I have wondered the same thing about the frequency of sets of five books, but I have never actually done a real or useful tally or anything, and sets of three books (The Instructor by Clement of Alexandria, Against Marcion by Ephraim, Apology to Autolycus by Theophilus, Against the Pelagians by Jerome, and others) seem fairly common, as well.

The gospel of Matthew has five sermons by Jesus, each ending with a formulaic phrase; it is usually supposed that this arrangement is in imitation of the Pentateuch, Matthew being a gospel which emphasizes Moses in many ways.