Tatian
a Christian apologist; born early in the 2d century (110, Zahn); was an Assyrian by birth; studied Greek philosophy; and wandered about as a sophist round the Roman world; but about 150 at Rome was won to Christianity by the simple charm of the Old Testament Scriptures and the example example of the purity and courage of the Christians. He became a disciple of Justin, in whose lifetime he wrote his "Oratio ad Græcos," a glowing and uncompromising exposure of the faults of heathenism as compared with the new "barbarian philosophy."
After Justin's death (166) Tatian fell into evil repute for heresies, and he retired to Mesopotamia, probably Edessa, writing with characteristic fearlessness and vigor, treatise after treatise, all of which have perished. He was certainly infected with gnostic notions of the universe, the supreme God, the demiurge, and the world of cons; but the notions of his which gave most offense were his excessive asceticism, his rejection of marriage and animal food, and adoption of the practices of the Encratites. Neither the place nor date of his death is known, but it took place perhaps at Edessa, and probably about 180.
Of his writings one maintained a place of importance in the Syrian Church for 200 years, and supplies one of the most interesting chapters in the history of sacred literature. This was the "Diatessaron," a gospel freely constructed out of the four gospels known to us, not a harmony in the modern sense, but a kind of patchwork gospel. This Harnack thinks was written in Greek; but Zahn and most other scholars, among them TATIAN Lagarde, Bäthgen, Lightfoot, and Hilgenfeld, in Syriac. There is no mention of the "Diatessaron" in any Latin writer before the middle of the 6th century. In the 5th century this work was used in the Syrian churches as the form in which the gospel was read, and further back still we find evidence of its use in the 3d century "Doctrines of Addài." The Syriac text of the "Homilies" of the former was edited by Professor Wright in 1869, and Zahn has proved that the key to the difficulty of his gospel citations is the fact that he used the "Diatessaron." Bar-Salibi, a Syrian bishop (12th century), distinctly states a that Ephraem wrote an exposition of Tatian's "Diatessaron." Lightfoot printed his famous article on Tatian (May, 1877), ignorant of the fact that a year before Dr. Moesinger of Salzburg had published at Venice a Latin translation of the same commentary, made as early as 1841 by Father Aucher of the Mechitarist monastery of San Lazzaro from the Armenian edition of Ephraem's works published in 1836 (4 vols.). The first scholar to make this remarkable discovery widely known was Ezra Abbot in his "Authorship of the Fourth Gospel" (1880).
In 1881 Zahn published his masterly monograph on Tatian's "Diatessaron," containing a reconstruction of the text from the Latin, based on Mœsinger's Latin version of Ephraem' Ephraem's Commentary, on the quotations in Aphraates, and occasional parallels with the "Codex Fuldensis." He showed that Tatian's original Syrian text agreed in great part with the Curetonian Syriac, and evidently preceded the Peshito or reformed Syriac text. The fresh interest thereby aroused in the question led Ciasca of the Vatican Library to examine anew the Arabic MSS. there. The existence of one was already known, it having been partially described by Assemani, Rosenmüller, and Akerblad. In 1886 Antonios Morcos, vicar-apostolic of the Catholic Copts, forwarded to Rome a 9th-century MS., which Agostino Ciasca edited for the jubilee of Pope Leo XIII., and this was found both in contents and arrangement to correspond with the work edited by Mæsinger.
Harnack thus sums up the conclusions that may be drawn from what may be considered as proved: (1) In Tatian's time there was still no recognized New Testament Canon, and the texts of the gospels were not regarded as inspired. (2) About 160, three of our four gospels were already in existence and authoritative, and the fourth on equality with the three synoptics. (3) The text of the gospels in 160 was substantially the same TATIAN as it is now, save that intentional changes and interpolations were made later, as the passage about the church being built on Peter the rock.