Apologist and rigorist. Of Middle Eastern origin, he became a Christian in Rome between 150 and 165. About 172 he returned to the E., where he is said to have founded the Encratites. His Oratio ad Graecos is a defence of the antiquity and purity of Christianity, combined with an attack on Greek civilization. His chief claim to fame is his ‘Diatessaron’ (q.v.).