Development of the New Testament canon a novelty in Irenaeus's time. "Against Heresies" 3.11.7 acknowledges that many heterodox Christians use only one gospel while 3.11.9 acknowledges that some use more than four. The success of Tatian's Diatessaron in about the same time period is "...a powerful indication that the fourfold Gospel contemporaneously sponsored by Irenaeus was not broadly, let alone universally, recognized." Irenaeus apparently quotes from 21 of the New Testament books and names the author he thought wrote the text. He mentions the four gospels, Acts, the Pauline epistles with the exception of Hebrews and Philemon, as well as the first epistle of Peter, and
Aramaic New Testament The Persian Harmony, The Arabic Diatessaron, and the Commentary on the Diatessaron by Ephrem the Syrian have provided recent insights into Aramaic origins. The Coptic Gospel of Thomas and the various versions of the medieval Hebrew Gospel of Matthew also have provided clues to Aramaic foundations in the New Testament especially the gospels. Many 19th Century scholars (H. Holtzmann, Wendt, Jülicher, Wernle, von Soden, Wellhausen, Harnack, B. Weiss, Nicolardot, W. Allen, Montefiore, Plummer, and Stanton) theorized that portions of the gospels, especially Matthew, were derived from an Aramaic source normally referred to as Q. The best evidence for at least