DIATESARÓN
A “harmony” of the four gospels made by Tatian, a disciple of Justin Martyr, around the year 170 AD.
Tatian had been a traveling pagan sophist before being converted in Rome around 150 AD.
After the death of Justin, in 166, Tatian fell into grave errors, and retired to Mesopotamia, where he wrote many treatises, all of which have disappeared.
Tatian’s main errors were his asceticism, his rejection of marriage and the consumption of animal flesh, and certain Gnostic doctrines about a demiurge and the aeons.
He was attacked by Irenaeus, Tertullian, Hippolytus, Clement of Alexandria, and by Origen himself. His Diatesaron is a kind of gospel made up of fragments of our four gospels, and not a harmony in the modern sense.