Church History by Eusebius Pamphilius
Chapter XVI.--The Epistle of Clement.
There is extant an epistle of this Clement which is acknowledged to be genuine and is of considerable length and of remarkable merit. He wrote it in the name of the church of Rome to the church of Corinth, when a sedition had arisen in the latter church. We know that this epistle also has been publicly used in a great many churches both in former times and in our own. And of the fact that a sedition did take place in the church of Corinth at the time referred to Hegesippus is a trustworthy witness.