c.110-172. Christian apologist and Gnostic. An Assyrian from Nisibitis on the Euphrates, he came to Rome about 150, was converted, and later became a pupil of Justin Martyr.* Like his master, he engaged in the defense of the faith against pagan misrepresentation. His “Address to the Greeks” (c.160) marks a retrograde step when compared with Justin's apologia. Unlike the latter's tolerant and courteous attitude to Greek learning and culture, Tatian had only mockery and contempt for pagan philosophy. After Justin's death he retired to Syria, where he became the founder of a group later called the Encratites.* Tatian's chief claim to fame is his Diatessaron,* used as a liturgical book in the Syrian Church until the fifth century.