The so-called Diatessaron receives its familiar title from a reference in Eusebius of Caesarea’s Ecclesiastical History, where it is said that “Tatian composed – I do not know how – a combination and compilation from the Gospels, and named it the Dia Tessarōn, which is still extant among some” (Eus. Hist. eccl. 4.29.6). Eusebius applies the same expression to Ammonius’ four-gospel synopsis in the letter to Carpianus that prefaces the canon tables incorporated in his edition of the Gospels.…