His
Oratio ad Graecos (Address to the Greeks) condemns paganism as worthless, and praises the reasonableness and high antiquity of Christianity. As early as
Eusebius, Tatian was praised for his discussions of the antiquity of
Moses and of Jewish legislation, and it was because of this chronological section that his
Oratio was not generally condemned. His other major work was the
Diatessaron, a "harmony" or synthesis of the four
New Testament Gospels into a combined narrative of the life of
Jesus.
Ephrem the Syrian referred to it as the
Evangelion da Mehallete ("The Gospel of the Mixed"), and it was practically the only gospel text used in Assyria during the 3rd and 4th centuries. In the mid 5th century the Diatessaron was replaced in those Assyrian churches that used it by the four original Gospels.
Rabbula, Bishop of
Edessa, ordered the priests and deacons to see that every church should have a copy of the separate Gospels (
Evangelion da Mepharreshe), and
Theodoret, Bishop of Cyrus, removed more than two hundred copies of the
Diatessaron from the churches in his diocese. The
Syriac Sinaitic manuscript of gospels was produced in between AD 411 and 435 as a result of his edict. A number of
recensions of the
Diatessaron are extant. The earliest, part of the Eastern family of recensions, is preserved in Ephrem's
Commentary on Tatian's work, which itself is preserved in two versions: an Armenian translation preserved in two copies, and a copy of Ephrem's original
Syriac text from the late 5th/early 6th century, which has been edited by
Louis Leloir (Paris, 1966). Other translations include translations made into
Arabic,
Persian, and
Old Georgian. A fragment of a narrative about the
Passion found in the ruins of
Dura-Europos in 1933 was once thought to have been from the
Diatessaron, but more recent scholarly judgement does not connect it directly to Tatian's work. The earliest member of the Western family of recensions is the Latin
Codex Fuldensis, written at the request of bishop
Victor of Capua in 545 AD. Although the text is clearly dependent on the
Vulgate, the order of the passages is distinctly how Tatian arranged them. Tatian's influence can be detected much earlier in such Latin manuscripts as the
Old Latin translation of the Bible, in
Novatian's surviving writings, and in the Roman Antiphony. After the Codex Fuldensis, it would appear that members of the Western family led an underground existence, popping into view over the centuries in an
Old High German translation (), a
Dutch (), a Venetian manuscript of the 13th century, and a
Middle English manuscript from 1400 that was once owned by
Samuel Pepys. In a lost writing entitled
On Perfection according to the Doctrine of the Savior, Tatian designates matrimony as a symbol of the tying of the flesh to the perishable world and ascribed the "invention" of matrimony to the devil. He distinguishes between the old and the new man; the old man is the law, the new man the Gospel. Other lost writings of Tatian include a work written before the
Oratio ad Graecos that contrasts the nature of man with the nature of the animals, and a
Problematon biblion, which aimed to present a compilation of obscure Scripture sayings. == Theology ==