New Testament the Anchor Bible Dictionary), may be the earliest known New Testament canon attributed to mainstream Christianity. It is similar, but not identical, to the modern New Testament canon. The oldest clear endorsement of Matthew, Mark, Luke, and John being the only legitimate gospels was written "circa" 180 AD. A four gospel canon (the "Tetramorph") was asserted by Irenaeus, who refers to it directly in his polemic "Against the Heresies", "It is not possible that the gospels can be either more or fewer in number than they are. For, since there are four zones of the world in which we live,
Synoptic Gospels eighteenth century, when Johann Jakob Griesbach published in 1776 a "synopsis" of the synoptic gospels. Instead of harmonizing them, he displayed their texts side by side, making both similarities and divergences apparent. Griesbach, noticing the special place of Mark in the synopsis, hypothesized Marcan posteriority and advanced (as Henry Owen had a few years earlier) the two-gospel hypothesis (Matthew–Luke). In the nineteenth century, researchers applied the tools of literary criticism to the synoptic problem in earnest, especially in German scholarship. Early work revolved around a hypothetical proto-gospel ("Ur-Gospel"), possibly in Aramaic, underlying the synoptics. From this line of inquiry, however,