A Greek musical term, meaning “a harmony of four parts,” which was the title given to a harmony of the four gospels composed by the Assyrian Christian Tatian* soon after a.d. 150. This was, so far as is known, the first time such a task was attempted. Tatian spent some time in Rome as a disciple of before returning to Assyria about 172. He founded a sect called the “Encratites”* who had certain ascetic practices including vegetarianism, so that in the Diatessaron is made to feed not upon locusts but upon milk and honey. The Diatessaron was very popular among Syriac-speaking Christians, but it is not clear whether it was first composed in Syriac. The title is Greek, and F.C. Burkitt even suggested that it might have been composed originally in Latin.
There are no extant MSS of the whole of the Diatessaron, though a fragment in Greek of's request for the body of Jesus was discovered in 1933 at a Roman fort at Dura-Europos on the Euphrates. In the fourth century, Ephraem Syrus wrote a commentary on the Diatessaron and an Armenian translation of this was discovered in 1836. A considerable portion of the Syriac original of this came to light in 1957. There are extant in addition two late Arabic MSS of the Diatessaron, a medieval Dutch harmony of the gospels which is dependent upon it, and the Latin Codex Fuldensis which has the order of the Diatessaron, though the text has been assimilated to the Vulgate. The Diatessaron was very popular among Syriac-speaking Christians, and steps had to be taken in the fifth century to abolish its use.
DIATESSARON dī’ ə tĕs’ ə ron. Diatessaron (a Gr. prepositional phrase, “by means of four”) the name traditionally given to a harmony of the gospels, compiled by Tatian, a Christian apologist of Assyrian origin resident in Rome in mid-2nd cent., until returning E in a.d. 172. In one ancient source, his compilation is called Diapente, “by means of five.” Both terms belong to Gr. music theory, meaning perfect fourth and perfect fifth respectively, these harmonies being most highly esteemed. Hence the work is defined as the “perfect harmony.” The use of Diapente may signify Tatian’s inclusion of apocryphal material from a fifth source, together with the four canonical gospels, since instances of apocryphal items are found in all sources.
It was prob. composed in Syr., but an early Lat. rendering may have been made in his lifetime. It is unlikely that its original language was Gr. The one certain Gr. fragment known is prob. a retranslation from Syr. The Diatessaron has not survived in its original form; a partially preserved Syr. commentary upon it by Ephraem (d. 378) was edited in 1963 and is the most direct source. An Armenian tr. has preserved the whole commentary. An Arab. VS of the harmony is known in several MSS. These two form the primary sources of knowledge, but may be supplemented from many others. A Pers. adaptation is known, and the harmony has left its mark in the E on the Armenian, Georgian, and Palestinian Syr. VSS; on their source, the old Syr. gospels; on quotations by Syr. Fathers; and in Manichaean lit. In the W, stemming from the early Lat. tr. mentioned, there are marked traces in the Old Lat. gospels, in Lat. harmonies adapted to the text of the Vulgate, and in vernacular harmonies in Old High Ger., Middle high Ger., Medieval Dutch, Middle Eng., and the Medieval Tuscan and Venetian dialects of Italian.
This astoundingly wide influence bespeaks Tatian’s literary skill and popular devotional appeal. The harmony even in the remotest sources bears traces of the extreme asceticism (Encratism) that forbade both sexual experience and the partaking of meat and wine. Some ancient references even assert that Tatian omitted the gospel genealogies of Jesus, although many of the sources have them. Three sure signs of Diatessaric influence upon any document are the assertion that both Joseph and Mary were of Davidic descent; that a great light shone on the Jordan at Jesus’ baptism; and that Jesus looked on the rich young ruler “lovingly.”
C. Peters, Das Diatessaron Tatians (1939); L. Leloir, Le Témoignage d’-Ephrém sur le Diatessaron (1962); B. M. Metzger, “Tatian’s Diatessaron and a Persian,” Chapters in the History of Textual Criticism (1963).