τὸ διὰ τεσσ€ρων. Eusebius is the first one to mention this Diatessaron, and he had evidently not seen it himself. After him it is not referred to again until the time of Epiphanius, who in his Hær. XLVI. 1 incorrectly identifies it with the Gospel according to the Hebrews, evidently knowing it only by hearsay. Theodoret (Hær. Fab. I. 20) informs us that he found a great many copies of it in circulation in his diocese, and that, finding that it omitted the account of our Lord’s birth, he replaced it by the four Gospels, fearing the mischief which must result from the use of such a mutilated Gospel. In the Doctrine of Addai (ed. Syr. and Engl. by G. Phillips, 1876), which belongs to the third century, a Diatessaron is mentioned which is without doubt to be identified with the one under consideration (see Zahn I. p. 90 sq.). Meanwhile we learn from the preface to Dionysius bar Salibi’s Commentary on Mark (see Assemani, Bibl. Or. I. 57), that Ephraem wrote a commentary upon the Diatessaron of Tatian (Tatianus Justini Philosophi ac Martyris Discipulus, ex quator Evangeliis unum digessit, quod Diatessaron nuncupavit. Hunc librum Sanctus Ephraem commentariis illustravit). Ephraem’s commentary still exists in an Armenian version (published at Venice in 1836, and in Latin in 1876 by Mœsinger). There exists also a Latin Harmony of the Gospels, which is without doubt a substantial reproduction of Tatian’s Diatessaron, and which was known to Victor of Capua (of the sixth century). From these sources Zahn has attempted to reconstruct the text of the Diatessaron, and prints the reconstructed text, with a critical commentary, in his Tatian’s Diatessaron. Zahn maintains that the original work was written in Syriac, and he is followed by Lightfoot, Hilgenfeld, Fuller, and others; but Harnack has given very strong reasons for supposing that it was composed by Tatian in Greek, and that the Syriac which Ephraem used was a translation of that original, not the original itself. Both Zahn and Harnack agree, as do most other scholars, that the work was written before Tatian became a heretic, and with no heretical intent. Inasmuch as he later became a heretic, however, his work was looked upon with suspicion, and of course in later days, when so much stress was laid (as e.g. by Irenæus) upon the fourfold Gospel, Christians would be naturally distrustful of a single Gospel proposed as a substitute for them. It is not surprising, therefore, that the work failed to find acceptance in the Church at large. For further particulars, see especially Zahn’s monograph, which is the most complete and exhaustive discussion of the whole subject. See also Harnack’s Ueberlieferung der Griech. Apologeten, p. 213 ff., Fuller’s article referred to in note 1, the article by Lightfoot in the Contemporary Review for May, 1877, and those by Wace in the Expositor for 1881 and 1882.