- William L. Petersen, “The Diatessaron: Its Creation, Dissemination, Significance, and History in Scholarship” (1994), is a very comprehensive look at the topic. Tatian’s Diaterssaron was not alone in the ancient world. Petersen mentions gospel harmonies by Theophilus of Antioch and Ammonius of Alexandria, which did not survive, noting that such harmonies were especially useful in combating pagan criticisms like those of Celsus (a philosopher) or Lucian (a satirist), of the variability and excessive creativity of Christian texts. Petersen surmises that Tatian’s version was “constructed from a very ancient form of the separate canonical gospels” which do not necessarily match up with our present texts. He goes into a lot of detail on this in pp.24-28. Efrem’s “Commentary on the Diatessaron” is a crucial source of information. A lot of the book examines Syriac, Arabic, and citations from other languages, in trying to determine what exactly the text was like. Unfortunately, the only known (small) fragment of a Diaterssaron is from a Greek version found at Dura-Europos. Apparently there were two streams of gospel harmonies, one based off of Matthew (Ammonius), and others based off of Luke (Tatian?) A medieval European harmony, C.C. De Bruin, “The Liege Diaterssaron” (1970), is a Dutch version, presumably based on earlier models. The editor, after starting off with John 1:1-5, moves to Luke 1:5, which recounts the Nativity story up to the birth of John (followed by an authorial interlude explaining the switch to Matthew, and the differing genealogies of Matthew and Luke).
- Once Joseph finds out Mary is pregnant, the narrative switches back to Luke. The narrative proceeds in general along those back-and-forth lines, with occasional episodes from John added chronologically. Passages which are found in all three synoptics are harmonized. Of particular interest is Easter morning, where all four narratives are presented as if in sequence, so that the tomb seems a bit like a train station at rush hour, with people continually coming and going.