endeavouring to compel these churches, which had hitherto kept Easter, with the Jews, on Nisan 14, to conform to the practice of Rome. On their refusal to abandon the custom of their forefathers, their reasons being given in a letter addressed to Victor by Polycrates, bp. of Ephesus, he had cut them off from his communion. This harsh treatment was highly disapproved by many even of those who, like the Roman bishop, kept Easter on the Sunday following the equinoctial full-moon. Among these was Irenaeus himself. In the name of all the Gallican churches he remonstrated with Victor, in a writing of which a considerable fragment is extant, reminding him of the example set by his predecessors, who had found no occasion in these differences of paschal observance for excommunicating their brethren of Asia Minor. Irenaeus (as Eusebius further informs us, H. E. v. 23) also appealed to other foreign bishops, but without any effect on the harsh determination of the Roman. Another writing of Irenaeus mentioned by Eusebius (H. E. v. 20), which seems to have referred to the same subject, was entitled περὶ σχίσματος and addressed to Blastus, head of the Roman Quartodecimans.
How long Irenaeus was bishop is uncertain. His death is commonly assigned to 202 or 203. This rests on the assumption that he was martyred under Septimius Severus. But such a martyrdom is by no means established. Tertullian, Hippolytus, Eusebius, Epiphanius, Ephrem, Augustine, Theodoret, are silent. In the Syriac fragments Irenaeus is frequently spoken of as "a disciple of Polycarp, bishop and martyr," but not himself honoured with the martyr's title either there or in any quotations from his writings. The first witness for his martyrdom is found in Jerome's commentary on Isaiah, written c. 410, where (c. 64) Irenaeus is spoken of as vir apostolicus episcopus et martyr; but when elsewhere treating ex professo of his life and writings (de Vir. Ill. c. 35), Jerome is silent as to his martyrdom. As Dodwell conjectures, the words et martyr may be an interpolation. If not, Jerome must have learnt the alleged fact subsequently to 392, when the de Viris Illustribus was written. There is no witness for it earlier than the 5th cent.
Writings.—The chief was the great work in five books against Gnosticism entitled Ἔλεγγος καὶ ἀνατροπὴ τῆς ψευδωνύμου γνώσευς, Detectio et eversio falso cognominatae agnitionis. (The full Greek title is found in Eus. H. E. v. 7; Phot. Bibl. Cod. 120 and elsewhere; cf. also frequent references to it by Irenaeus in the praefationes to bks. ii. iv. v. and the conclusion of bk. iv.) It is commonly cited under the briefer title πρός αἱρέσεις (contra Haereses) We possess it entire in the Latin version only, which, however, must have been made from the Greek original very soon after its composition, since the Latin was used by Tertullian some ten years after, in his tractate adv. Valentinianos. Its translator was a Celt (witness the barbarous Latinity); probably one of the clergy of Lyons. Most of the original work being now lost, the slavish literality of the translator imparts to his version a very high value. Many obscurities of expression, arising in part from a misunderstanding of the Greek idiom, admit an easy solution when translated back into Greek. Beside this Latin version, which appears to have soon superseded the Greek original in the Western church, there was a Syriac translation, of which numerous fragments are extant and were first put together by Harvey in his ed. of Irenaeus (ii. 431 seq.). They are derived from the Brit. Mus. collection of Nitrian MSS., some of which are as old as the 6th, 7th, and 8th cents. (cf. Harvey, ii. 431, note). To these are added (Nos. xxi. xxxi. and xxxii.) fragments of an Armenian interpolated version first published by Pitra in his Spicilegium Solesmense, t. i. (Paris, 1852). Of these No. xxi. only is taken from the work Against Heresies. The almost entire agreement between these Syriac fragments and the Old Latin version further witnesses its genuineness and fidelity. The Greek original, said to have been still extant in the 16th cent., was made great use of by Hippolytus (or whoever wrote the Philosophumena), Epiphanius, and Theodoret. To the numerous extracts in these writers, esp. the first two, we owe the greater part of the original Greek of bk. i.—the preface and cc. 1–21 entire, and numerous fragments besides. Of the other books, the Greek has come down to us in isolated passages, mostly through citations by Eusebius. The ed. of Wigan Harvey (2 vols. Camb. 1857) is based on a careful collation of the Codices Claromont. and Arundel. His Prolegomena contain minute investigations into the origin, characteristics and main phenomena of Gnosticism, as well as concerning the life and writings of Irenaeus.
Against Heresies was written in Gaul. (Irenaeus says so expressly, lib. i. praef. 3, cf. i. 13, 7. We follow Massuet's division of chapters.) The date of composition is determined iii. 3, 3, in which he speaks of Eleutherus as then twelfth in succession to the apostles on the episcopal chair of Rome (νῦν δωδεκάτῳ τόπῳ τὸν τῆς ἐπισκοπῆς ἀπὸ τῶν ἀποστόλων κατέχει κλῆρον Ἐλεύθερος). According to this, the third book was written at the earliest a.d. 174 or 175, at the latest a.d. 189 (cf. Chronologie der röm. Bischöfe, pp. 184 sqq.). The commencement and completion of the work were possibly some years apart, but we cannot put the date of bks. iv. and v. so late as the episcopate of Victor (189–198 or 199). We may tentatively assume 182, the mid-period of Eleutherus's episcopate, or (since the first two books alone appear to have been written immediately after each other—cf. the prefaces to bks. ii. and iii.–v.) we may propose from a.d. 180 to 185 as the date of the whole work. To assign a more exact date is hopeless. That Irenaeus wrote as bishop, and not earlier than 178 as presbyter, is by far most probable, though it cannot be drawn with absolute certainty from the words of the preface to bk. v. to which Massuet appeals.
As the first external motive for its composition, Irenaeus himself mentions (lib. i. praef.; ii. 17, 1; iii. praef.) the request of a friend for some instruction as to the heretical opinions of the Valentinians and how to refute them. The recent spread of the Valentinian sect through the Rhone district had already led Irenaeus to acquaint himself particularly
