The Diatessaron is a narrative of the life of Jesus composed by combining all four gospels into a single text. It was written by Tatian in the second century. It is unclear whether he composed it in Greek or Syriac. Tatian had come to Rome from 'Assyria' and become a disciple of Justin Martyr; after the death of Justin he fell into the heresy of the encratites, and returned to Syria. It is unclear whether he wrote the Diatessaron before or after his return to the East.
Both the Greek and Syriac texts are lost. Latin and Arabic translations now exist, both of which have been modified to reflect later vulgate biblical texts. There are also other biblical harmonies of the same kind such as those in Latin, Middle Persian, Anglo-Saxon and Dutch, which are not in fact derived from the Diatessaron.
The composition of the Diatessaron
Eusebius of Caesarea (HE. IV.29.6) tells us that:
- Tatian composed in some way a combination and collection of the gospels, and gave this the name of The Diatessaron (to\ dia\ tessa/rwn) and this is still extant in some places.
Theodoret of Cyrrhus (d.457/8), PG 83, "Haereticarum fabularum compendium ad Sporacium," 1.20 (= pp. 370-71); more familiarly known by the title, "Treatise on Heresies", writes:
- He [Tatian] composed the Gospel which is called Diatessaron, cutting out the genealogies and such other passages as show the Lord to have been born of the seed of David after the flesh. This work was in use not only among persons belonging to his sect, but also among those who follow the apostolic doctrine, as they did not perceive the mischief of the composition, but used the book in all simplicity on account of its brevity. And I myself found more than two hundred such copies held in respect in the churches in our parts. All these I collected and put away, and I replaced them by the Gospels of the four Evangelists.
(No English translation of this work exists: the quotation is taken from J. M. Fuller’s article “Tatian” in W. Smith and H. Wace, A Dictionary of Christian Biography (4 vols.; London: John Murray, 1887) 4.795, via Leslie McFall, "Tatian's Diatessaron: Mischievous or Misleading?" Westminster Theological Journal 56.1 (Fall 1994): 87-114)
See also Ephrem for his commentary on the Diatessaron.