The widely read Nestle-Aland Novum Testamentum Graece opens not with Matthew's genealogies but with Eusebius of Caesarea's brief Letter to Carpianus. To Carpianus introduces the Eusebian Canons, a complex system of cross-references across the four canonical gospels that guides readers to parallel passages among gospel narratives. Eusebius's canon tables segment the four canonical gospels into a total of 1,162 sections, and then tabulate these sections into ten tables (canons) that match what Eusebius records as parallel passages. In the margin of Eusebius's gospel text, each segment is labeled with a section number and (below it) a canon number; in turn, in each canon table readers can check which gospel section has parallels (selected by Eusebius) in other gospels.
To explore an example chosen at random: at John 12:23 (“‘The hour has come so that the Son of Man may be glorified,’” declares Jesus in Jerusalem before his passion), the reader can look in the margin and see – I translate into Arabic numerical notation – 103/4. This means that this saying is section 103 of John, and lies in Eusebius's Canon Table 4, the table that matches passages common to Matthew, Mark, and John but not Luke. In that Table, the reader will see references to sections 299 of Matthew and 180 of Mark. Eusebius's Matthean and Markan parallels (Matthew 26:45–46 = Mark 14:41–42), both set in Gethsemane, also involve Jesus saying, “the hour has come,” and both invoke the Son of Man; but instead of John's glorification, Matthew and Mark have the Son of Man betrayed into sinners’ hands. Eusebius's juxtaposition of these three passages confronts readers with a paradox, contrasting, on the one hand, John's identifying Jesus's “hour” with glorification with, on the other hand, Matthew and Mark making Jesus's “hour” the moment of his arrest.
Recent scholarship on the Canons has either interpreted Eusebius's reference system as an apologetic against accusations that the canonical gospels contradicted one another, or, more persuasively, contextualized this reference apparatus in the tradition of Alexandrian scholarship. (On the latter, see Matthew R. Crawford, The Eusebian Canon Tables: Ordering Textual Knowledge in Late Antiquity [Oxford; New York: Oxford University Press, 2019].) Jeremiah Coogan's book, by contrast, studies the Eusebian Canons in the narrower context of gospel writing and reading. Coogan's thesis, amply signposted throughout the book, is that Eusebius's system of cross-references constituted no less than a rewriting of the fourfold gospel.
Coogan's first, introductory chapter contextualizes Eusebius and frames Coogan's study of the Canons. Coogan persuasively centers Caroline Levine's concept of “affordances,” features of an object that invite and facilitate potential, contingent uses of that object. As affordances, Eusebius's cross-references become not merely a discrete scholarly project but generate creative gospel reading. Chapter 2 then compares Eusebius's Canons with its predecessors (astronomical tables and parallel texts such as Origen's six-column Jewish Bible, the Hexapla). The chapter offers an excellent survey of the paratextual system with plentiful illustrative images.
Chapter 3 compares Eusebius's Canons to earlier gospel composition beginning with Mark. Coogan characterizes Eusebius's work as curation, “the productive limitation of a corpus and of the ways one encounters it” (62). Coogan then constructs an incisive typology of tactics for rewriting a text: rewriters can omit, abbreviate, absorb, re-sequence, juxtapose, frame, correct, or harmonize their source-texts. Previous evangelists Matthew and Luke (both with Mark), Tatian, Marcion, and Ammonius, Coogan shows, performed these rewriting operations. Eusebius's canons were distinctive in retaining the integrity and sequence of the fourfold whole but guiding readers to notice cross-textual commonalities, thus resequencing reading (86–87).
Chapter 4 explores the common traits that associated the gospel passages linked by Eusebius's canons. Coogan calibrates reader expectations effectively by noting that that the key term that Eusebius uses to denote similar passages, ta paraplēsia, denotes similar but not identical passages. Coogan then shows that Eusebius tended – as shown in the example above of John's, Mark's, and Matthew's pronouncements that Jesus's “hour has come” – to seek thematic rather than historical parallels, even if the parallels involved contrasting contexts or divergent details. For example, despite clear divergences Eusebius linked the miraculous catch of fish early in Luke (5:4–7) with the post-resurrection haul in John (21:1–11) and the healing of the centurion's slave in Matthew (8:5–10) and Luke (7:1–9) to the healing of the official's son in John (4:46–54). Eusebius's canons, Coogan emphasizes, suggest differences as well as commonalities between related passages. This was no apologetic strategy, instead aiming to prompt deep, honest textual engagement from readers committed to the fourfold gospel's scriptural status.
Chapter 5 surveys the reception of Eusebius's canons across New Testament manuscripts in twelve languages. Later scholars based marginal notes on the Canons, built them into chapter titles, or excerpted based on its divisions. The chapter, richly illustrated with examples of manuscripts transmitting Eusebian references, raises fruitful questions. Did commentators end up comparing passages based on Eusebius's canons? Did homilists appeal to common passages or wrestle with the differences in Eusebius's parallels? Did Christian theology, morality, or ecclesiology take any distinctive directions based on Eusebius's juxtapositions?
Eusebius's canons certainly expanded the affordances for the gospels in striking directions; they were a consequential act of curation. But did his curation and affordances constitute, as Coogan asserts, fully fledged rewriting? This reviewer would not go so far. Unlike with Matthew's, Luke's, Marcion's, or Tatian's gospels, Eusebius's choice to arrange the canons by evangelist reinforced the integrity of the four canonical gospels and their respective texts – indeed, Eusebius's system entrenched the sacrality of the quartet's complete text (excepting only the longer ending of Mark, omitted by Eusebius). Resistant readers, meanwhile, have at their ready disposal the means to reject Eusebius's suggested passageways within the gospels.
Two contrasting passages from Eusebius's other works may illustrate. Praeparatio Evangelica 11–13 selectively excerpts Platonic texts to portray Plato as copying biblical principles, while in Ecclesiastical History 2:23, 2:26, 3:5–8 Eusebius quotes Josephus's Jewish War misleadingly to make Josephus confirm that the Jerusalem temple fell due to Jewish rejection of Jesus. Both passages involve selection, omission, absorption, re-sequencing, juxtaposition, reframing, and harmonization of previous texts, more and more systematic operations of rewriting than Eusebius's canons exhibit. In all, although Coogan's thesis that Eusebius “rewrote” the gospels remains debatable, his wide evidence (with excellent images) and supple methods open numerous lines of research that subsequent scholars should pursue.