Encyclopædia Britannica, Ninth Edition/Tatian
Tatian soon returned from Greece to Rome, and came into close relations with the famous apologist Justin, whom he reverenced greatly. He himself established a school, to which the afterwards celebrated ecclesiastical writer Rhodon belonged for a time. So long as Justin lived (i.e. till 166) Tatian's doctrines excited no feelings of offence in the Christian community, although even in his Oratio there are germs of questionable and unorthodox views. These germs, however, he continued to develop until about 172; and, as about this very time the Roman church became severely opposed to everything Gnostic and heretical, a rupture was inevitable; the date of the breach is given by Eusebius (doubtless following Julius Africanus) as having been 172. But the teaching of Tatian had really become open to challenge. He drew a distinction between the supreme God and the demiurge, considering the latter to be good in his nature indeed, but quite a subordinate being; he accepted the doctrine of a variety of æons; he utterly rejected marriage and the use of animal food; he denied the blessedness of Adam; he began to abandon the allegorical interpretation of the Scriptures and to see genuine difficulties and contradictions in them; he sought to demonstrate from the epistles of Paul the indispensableness of the most rigid asceticism; but indeed all his "heresies" (and he has also been charged with docetism) have their explanation in this desire of his to establish a theoretical basis for his doctrine of the Christian duty of complete world-renunciation. He joined the "Encratites," a sect which indeed had existed before this time, but which received new life from his presence. Of his numerous writings belonging to this period nothing has survived the hostility which sought their repression save a few titles (βιβλίον προβληάτων περὶ ροῠ κατὰ τὸν σωτῆρα καταπτισμοῠ, &c.) and one Or two very interesting fragments in the works of Clement of Alexandria, Origen, and Jerome. Clement of Alexandria seems personally to have known Tatian, and even to have been his pupil for a time. Soon Tatian began also to be assailed in writing by the teachers of the church, and to be set aside as a very prodigy among heretics, and as a man who united the errors of Marcion with those of Valentine. Musanus, Rhodon, Irenieus, the author of the Muratorian fragment (see below), Tertullian, Hippolytus, Clement of Alexandria, and Origen all took part in refuting him.
Towards the end of his life, or perhaps even between 152 and 172, Tatian went from Rome to Mesopotamia, and there—probably in Edessa—wrought a great deal. It is probable that he was in Rome about the year 172, but whether he died there or in his native country is not ascertained. It is very possible that in Syria, where ecclesiastical matters had not been developed so far as in the West, the doctrines of Tatian met with toleration within the Christian communities, but neither of this can we be certain. But this we do know, that a work of Tatian's not yet mentioned, the Diatessaron, held its ground in the Syrian churches and even in ecclesiastical use for two whole centuries.
The Diatessaron is a gospel very freely and boldly constructed by Tatian out of the four Gospels known to us. It cannot have been produced during his latter years, for all traces of dualism are absent. On the other hand, however, it exhibits certain peculiarities of the theology of its compiler. Probably one would not so far wrong in assigning it to the first years of the reign of Marcus Aurelius. It was written by Tatian in Greek, not in Syriac as Zahn has tried to make out;—this is shown—(1) by the title, it being known even among the Syrians as Diatessaron; (2) by a few Greek fragments which still survive; (3) by the Latin redaction which it received in the 6th century; (4) by its rejection in the Muratorian fragment—for that the word "m-tia-i," carelessly corrected by the transcriber, stood originally "tatiani" may be regarded as certain. In estimating the work scholars were formerly entirely dependent on certain meagre notices in Eusebius, Theodoret, Ephraem Syrus, Epiphanius, and the later Syrians, but we have recently become possessed of large portions of it, and are now in a position to form for ourselves an idea of its character and plan. In 1877 there was published a Latin translation, by Aucher the Mechitarist, of Ephraem's gospel commentary, which had been preserved in Armenian, and it then became apparent that Ephraem had taken the Diatessaron as his basis. This led to further research.  Recognizing with other scholars that other Syrian writers also, down to the middle of the 4th century, had used the Diatessaron (Theodoret tells us that in his diocese alone he caused more than 300 copies to be withdrawn from use), Zahn undertook the laborious task of restoring the work with the help of Ephraem's commentary and other sources. In details much of what Zahn has given as belonging to the text of the Diatessaron remains problematical,—in particular he has not been sufficiently careful in his examination of the work of Aphraates,—but in all the main points his restoration has been successful. The rediscovery of such a work is in a variety of ways of the very highest importance for the early history of Christianity. (1) It is of interest for the history of the canon. It shows that in Tatian's time there was still no recognized New Testament canon, and that the texts of the Gospels were not regarded as inspired. He could not possibly have treated them with such freedom had they been held to be otherwise. But the ecclesiastical use made of his work in Syria shows that Tatian intended it for the church, and, as we are informed further by Eusebius that Tatian also edited the Pauline epistles, we are entitled to conclude that, like Marcion, he wished to frame a special New Testament canon. (2) It is of importance for the Gospels as we now have them. We learn from the Diatessaron that about 160 A.D. our four Gospels had already taken a place of prominence in the church and that no others had done so; that in particular the Fourth Gospel had taken a fixed place alongside of the three synoptics. (3) As regards the text of the Gospels, we can conclude from the Diatessaron that the texts of our Gospels about the year 160 already ran essentially as we now read them, but that intentional changes were not wanting about the middle of the 2d century. Thus, for example, Tatian in his Gospel according to Matthew found nothing about the “church” and about the building of the church upon Peter the rock. These sentences therefore are very probably of later interpolation. (4) It is of importance for the light it throws on Tatian’s Christianity. The Syriac translation of the Diatessaron still falls within the 2d century, but Zahn was mistaken in assuming it to presuppose a prior Syriac translation of the separate Gospels (the so-called Syrus Curetonianus); Baethgen has shown the latter to be the later. It was only gradually that the “evangelium der Getrennten” superseded the “evangelium der Gemischten.”
The best editions of the Oratio ad Græcos are those of Worth (Oxford, 1700), Maranus (Paris, 1742), and Otto (Jena, 1851). See Daniel, Tatian der Apologet, 1S37; Zahn, Tatian's Diatessaron, Erlangen, 1881 (compare also his Evang. Comm. des Theophilus, Erlangen, 1883, p. 286 sg.); Harnack, Texte u. Untersuchungen z. Gesch. d. altchr. Lit., i. 1; Id., Ztschr. f. Kirchengesch., iv. 471 sq.; and Tatian's Rede an die Griechen übersetzt u. eingeleitet, Giessen, 1884; Hilgenfeld, Ketzergesch., Leipsic, 1884; Möller, art. “Tatian,” in Herzog-Plitt's Encykl., vol. xv.; and Donaldson, Hist, of Christ, Lit., iii. p. 3-62. (a. ha.)
- The author of the Acta Archelai treats him as a heretic.
- See Zeitschr. f. d. luth. Theol., 1874 and 1875; Zeitschr. f. wiss. Theol; 1877; Zeitschr. f. Kirchengesch., iii. p. 400.
- See Credner, Einl., i. 437 sq.; Semisch, Tatiani Diatessaron, 1856.
- Evangelii Concordantis Expositio facta a S. Ephraemo, Venice.
- See Harnack, Ztschr. f. Kirchengesch., iv, p. 471 sq.
- Zahn, Tatian's Diatessaron, 1881.
- Evangelienfragmente: Der Griechische Text des Cureton'schen Syrers, Leipsic, 1885.
- On the Diatessaron, its later history and various editions, see (besides Zahn, as cited above) the Codex Fuldensis, ed. Ranke, 1868; Schmeller, Ammonii Alex. quæ et Tatiani dicitur Harmonia Evang., 1841; Sievers, Tatian, Lat. and Ger., Paderborn, 1872; Martin, “De Tatiani Diatessaron Arabioa Versione,” in Pitra's Analecta Sacra, vol. iv. (1883), pp. 465, 487.