Saint, a celebrated bishop of Lyon of the second century. His birth is commonly assigned to the year A.D. 120, though some make it as late as A.D. 140. It is not known with certainty what country gave him birth, yet from his modes of thought, as discernible in the fragments of his writings which have come down to us, it has been conjectured, with probability, that he was a Greek. That he possessed so little skill in writing Greek may be explained by the fact that he had mostly to speak another language. From the mention which he makes of his having been in youth the disciple of Polycarp, it is supposed that he may have been a native of Asia Minor. After the valuable training which he received from such a preceptor as the venerable Bishop of Smyrna, he was sent on a mission to Pothinus, Bishop of Lyon, in Gaul—upon what occasion is unknown. He was elevated to the sacerdotal office in A.D. 177, and sent by the churches of Vienne and Lyon on some ecclesiastical business, to Eleutherius, Bishop of Rome. Meanwhile the flames of persecution raged, and Pothinus having suffered martyrdom, Irenaeus was appointed bishop in his place. He is represented as a zealous preacher of the gospel amongst the surrounding idolaters, and a wise ruler amongst his own flock. When external peace was restored to the church, there sprang up violent controversies with Gnostics, Valentinians, and whole hosts of visionaries. These occasioned Irenaeus great uneasiness, for he was of a pacific disposition. He did not, however, refrain from entering the lists against error; and the only one of his works which has come down to us is that Against Heresies.

The original Greek of it has nearly all perished, and the uncorrect Latin translation which we have was made, according to Dodwell, near the end of the fourth century. It consists of five books, which were published, apparently, at different times. Irenaeus was well qualified to write such a work, as he has been considered to have possessed a more extensive acquaintance with heathen mythology, literature, and philosophy, than any other man of his day. In combating Gnosticism, he takes the common view, that it sprang from philosophy, and in opposition he appeals chiefly to tradition and the consent of the church. He regards piety and love as of far more importance than mere knowledge; and, indeed, as a general characteristic of our author, it may be noticed, that he stands distinguished above his successors in Christian philosophy for the pre-eminence which he assigns to the ethical over the physical element in man. He was the first of the fathers to place in a clear light the truth that the education of man consists in acquiring the knowledge of God, "Vita hominis autem visio Dei." All things reveal Him, but the process is gradual, and the Gnostics err in repining at the slowness of the growth of their knowledge. The permission of evil itself is connected with the education of the species. Man, as possessing liberty, is good or bad, not from nature, but from choice. Whatever difficulties may be raised about the possibility of our knowing God, Irenaeus, on the other side, takes the ground that our reason tells us there is a God; nor can this Deity be dispensed with by the fiction of an endless succession of beings, for however long the series may be, we must ultimately come to the one on which all the others depend. He charges the Gnostics with making a greater God than God, and then denying his existence. He stated very clearly the doctrine of the resurrection like Plato; and with his characteristic horror of the unmeasured, he held that only a limited and definite number were chosen to life. Irenaeus is the first church teacher in whom we find any allusion to infant baptism, and with him it is seen as the medium through which the principle of sanctification, imparted by Christ to human nature from its earliest development, became appropriated to children. The child born in a Christian family was, according to him, to have this advantage above others, that he did not first come to Christianity out of heathenism or the sinful life of nature; but from the first dawning of consciousness unfolded his powers under the imperceptible preventing influence of a sanctifying ennobling religion. In such a life regeneration did not constitute a new crisis beginning at a definable moment, but it was to begin imperceptibly, and so to proceed through the whole life. Hence baptism was to be administered to a child at the very outset. His views on this subject were combated by Tertullian.

Besides his work Against Heresies, Irenaeus wrote a letter to Florinus, entitled, Monarchy, or God not the Author of Evil. Florinus had imbued first the errors of the Gnostics, and then those of the Valentinians. These latter were refuted by Irenaeus in a work called Ogdoad, or the Number Eight. Against Blastus he wrote his treatise On Schism, in which he entered into the controversy about the time of the celebration of Easter. He also wrote a letter remonstrating with Victor, the haughty Bishop of Rome, for his anathemas against the churches in Asia. The divisions regarding Easter at this time were painful to Irenaeus, for to him the unity of the church was of paramount importance. Being himself originally from Asia, he formed in this and in the Gnostic controversies, as it were, a bridge between the East and the West. From the school of John in Asia Minor, there had gone forth an influence which tended to purge the church from the caprice of Gnostic theosophy, and sought faithfully to preserve the peculiar fundamental doctrines of Christianity. This tendency Irenaeus transmuted into the conflicting rush of opinions which then threatened to oversweep the Christianity of the West. He formed the link of connection between Asia Minor and Rome, and in many respects represented in himself what was peculiar to them both. With a sober practical spirit, and a peculiarly sound and discriminating tact in determining what was of living moment in all doctrines, his humility and good sense presented a remarkable contrast to the arrogant pretensions of the Gnostic teachers, and the extreme views of the followers of Montanus. It was not, however, till Tertullian arose that the absorbing interest of practical Christian life found a scientific expression, and the devoutly living element in Christianity being projected upon a scientific plan was lifted a step higher above the shifting tides of popular philosophy. Besides the foregoing works, Eusebius mentions one On Knowledge, against the Gentiles, two addressed to Marcian, On the Preaching of the Apostles, and a collection of discussions of various subjects.

The weak point in the writings of Irenaeus is his extravagant regard for traditions. He carefully collected these, and plumed himself on having seen and known many who had been personally acquainted with the apostles themselves. Some of the absurd notions which he entertained regarding the millennium may be seen in Middleton's Free Inquiry. It ought not, however, to be forgotten that with all the sensuousness which clouded his view on this and other subordinate points, there was blended a love of holiness purely spiritual, and an exalted idea of the supreme blessedness of fellowship with God. The thousand years' reign, with all its sensuous accessories, he regarded as only a preparatory step for the righteous, who were there to be trained for a more exalted heavenly existence in which they were afterwards to reap a full manifestation of the divine glory.

The time and circumstances of his death are not known. It has been asserted, that along with 9000 confessors to the truth in the district of Lyon, he received the crown of martyrdom in the beginning of the third century. But to this there is an insuperable objection in the total silence of Eusebius, Tertullian, and all the early historians. His life has been written by Gervaise in 2 vols. 12mo, Paris, 1723. His works were published by Erasmus in 1526, and by Fenardent in 1596. These were reprinted by Grabe, at Oxford, in 1702. In 1710 appeared René Massuet's edit- tion in Paris, and shortly afterwards that of Pfaff with the newly discovered fragments, which, however, have been considered spurious. See Lardner's Credibility, &c., Dodwell On Irenaeus, Tillemont and Fleury's Eccles. Hist.