Diatessaron book

I'd like particularly to draw attention to Ulrich Schmid, Unum ex quattuor: Eine Geschichte der lateinischen Tatianueberlieferung (Herder, 2005). Entitled 'One out of four: A history of the Latin tradition of Tatian', this work explains the history of running harmonies of the four Gospels in the West. Tatian had originally rolled the four Gospels into one account in the second half of the second century, but his harmony no longer survives. Textual critics argued that daughter versions in Western languages (e.g. Middle English, Old High German), when they agreed with daughter versions in Eastern languages (e.g. Arabic, Persian), could give us important information about the text of the second century. In a meticulous study Schmid shows that all of the Western harmonies could go back to a single Latin manuscript. All of their 'agreements' with Eastern witnesses would then become coincidental. From initial reading it seems a brilliant demolition job on a whole load of previous scholarship. The whole textbook story about reconstruction of the Tatian's harmony (the Diatessaron) being essential for study of the early Gospel text is shown to have elements of the mythic about it.