Eusebius the Historian, in his Ecclesiastical History, Book v chapter 20, mentions three writings of S. Irenæus thus: Against those who at Rome were debasing the right Faith, Irenæus composes diverse Epistles. One he inscribed, To Blastus on the Schism, another, To Florinus, On Monarchy, or, On God being not the Author of evils. For this opinion did he appear to advocate. On his account again when drawn away into the error of Valentinus, is Irenæus’ work, On the Ogdoad, compiled: wherein he signifies that he himself “has received the first succession from the Apostles.” Eusebius then gives these two first extracts.
Again chapter 24, Eusebius introduces a third fragment by saying that S. Irenæus in the name of the brethren through Gaul, over whom he was, set forth that the Mystery of the Lord’s Resurrection should be observed only on Sunday, and in very many words besides duly admonishes Victor [Bishop of Rome] that he should not cut off whole churches of God which kept the tradition of ancient custom, and adds these words.
In chapter 26, he mentions three other writings of S. Irenæus, Concerning knowledge: To the Brother Marcian, in proof of the Apostolic preaching: and a Book of diverse disputations, wherein he makes mention of the epistle to the Hebrews, and of what is called The Wisdom of Solomon, citing from them.