From his Oratio (chap. 42) we learn that Tatian was born in Assyria, and that he was early educated in Greek philosophy, from which we may conclude that he was of Greek parentage,—a conclusion confirmed by the general tone of the Oratio (cf. Harnack, Ueberlieferung der Griech. Apol. p. 199 sq., who refutes Zahn’s opinion that Tatian was a Syrian by race). We learn from his Oratio also that he was converted to Christianity in mature life (cf. chap. 29 sq.). From the passage quoted in the present chapter from Irenæus, we learn that Tatian, after the death of Justin (whose disciple he was; see also chap. 16, above), fell into heresy, and the general fact is confirmed by Tertullian, Hippolytus, Clement of Alexandria, Origen, and others. Beyond these meager notices we have little information in regard to Tatian’s life. Rhodo (quoted in Bk. V. chap. 13, below) mentions him, and “confesses” that he was a pupil of Tatian’s in Rome, perhaps implying that this was after Tatian had left the Catholic Church (though inasmuch as the word “confesses” is Eusebius’, not Rhodo’s, we can hardly lay the stress that Harnack does upon its use in this connection). Epiphanius gives quite an account of Tatian in his Hær. XLVI. 1, but as usual he falls into grave errors (especially in his chronology). The only trustworthy information that can be gathered from him is that Tatian, after becoming a Christian, returned to Mesopotamia and taught for a while there (see Harnack, ibid. p. 208 sq.). We learn from his Oratio that he was already in middle life at the time when he wrote it, i.e. about 152 a.d. (see note 13, below), and as a consequence it is commonly assumed that he cannot have been born much later than 110 a.d. Eusebius in his Chron. (XII. year of Marcus Aurelius, 172 a.d.) says, Tatianus hæreticus agnoscitur, a quo Encratitæ. There is no reason to doubt that this represents with reasonable accuracy the date of Tatian’s break with the Catholic Church. We know at any rate that it did not take place until after Justin’s death (165 a.d.). In possession of these various facts in regard to Titian, his life has been constructed in various ways by historians, but Harnack seems to have come nearest to the truth in his account of him on p. 212 sq. He holds that he was converted about 150, but soon afterward left for the Orient, and while there wrote his Oratio ad Græcos; that afterward he returned to Rome and was an honored teacher in the Church for some time but finally becoming heretical, broke with the Church about the year 172. The arguments which Harnack urges over against Zahn (who maintains that he was but once in Rome, and that he became a heretic in the Orient and spent the remainder of his life there) seem fully to establish his main positions. Of the date, place, and circumstances of Tatian’s death, we know nothing. Eusebius informs us in this chapter that Titian left “a great many writings,” but he mentions the titles of only two, the Address to the Greeks and the Diatessaron (see below, notes 11 and 13). He seems, however, in §6, to refer to another work on the Pauline Epistles,—a work of which we have no trace anywhere else, though we learn from Jerome’s preface to his Commentary on Titus that Tatian rejected some of Paul’s epistles, as Marcion did, but unlike Marcion accepted the epistle to Titus. We know the titles of some other works written by Tatian. He himself, in his Oratio 15, mentions a work which he had written On Animals. The work is no longer extant, nor do we know anything about it. Rhodo (as we are told by Eusebius in Bk. V. chap. 13) mentioned a book of Problems which Titian had written. Of this, too, all traces have perished. Clement of Alexandria (Strom. III. 12) mentions an heretical work of Tatian’s, entitled περὶ τοῦ κατὰ τὸν σωτῆρα καταρτισμοῦ, On Perfection according to the Saviour, which has likewise perished. Clement (as also Origen) was evidently acquainted with still other heretical works, especially one on Genesis (see below, note 7), but he mentions the title only of the one referred to. Rufinus (H.E. VI. 11) says that Tatian composed a Chronicon, which we hear about from no other writer. Malalas calls Tatian a chronographer, but he is evidently thinking of the chronological passages in his Oratio, and in the absence of all trustworthy testimony we must reject Rufinus’ notice as a mistake. In his Oratio, chap. 40, Tatian speaks of a work Against those who have discoursed on Divine Things, in which he intends to show “what the learned among the Greeks have said concerning our polity and the history of our laws and how many and what kind of men have written of these things.” Whether he ever wrote the work or not we do not know; we find no other notice of it. Upon Tatian, see especially Zahn’s Tatian’s Diatessaron and Harnack’s Ueberlieferung, &c., p. 196; also Donaldson’s Hist. of Christ. Lit. and Doct. II. p. 3 sqq., and J. M. Fuller’s article in the Dict. of Christ. Biog.