Eusebius and Canon of New Testament
Eusebius Pamphilius was bishop of Caesarea in Palestine from 314 to 339 and the first known Church historian. His main writing is Church History, in which he gave us his list of New Testament books in 324 (English translation from The Nicene and Post-Nicene Fathers, Series II, Vol. 1)
Since we are dealing with this subject it is proper to sum up the writings of the New Testament which have been already mentioned. First then must be put the holy quaternion of the Gospels; following them the Acts of the Apostles. After this must be reckoned the epistles of Paul; next in order the extant former epistle of John, and likewise the epistle of Peter, must be maintained. After them is to be placed, if it really seem proper, the Apocalypse of John, concerning which we shall give the different opinions at the proper time. These then belong among the accepted writings.
Among the disputed writings, which are nevertheless recognized by many, are extant the so-called epistle of James and that of Jude, also the second epistle of Peter, and those that are called the second and third of John, whether they belong to the evangelist or to another person of the same name. Among the rejected writings must be reckoned also the Acts of Paul, and the so-called Shepherd, and the Apocalypse of Peter, and in addition to these the extant epistle of Barnabas, and the so-called Teachings of the Apostles; and besides, as I said, the Apocalypse of John, if it seem proper, which some, as I said, reject, but which others class with the accepted books. And among these some have placed also the Gospel according to the Hebrews, with which those of the Hebrews that have accepted Christ are especially delighted. And all these may be reckoned among the disputed books.
But we have nevertheless felt compelled to give a catalogue of these also, distinguishing those works which according to ecclesiastical tradition are true and genuine and commonly accepted, from those others which, although not canonical but disputed, are yet at the same time known to most ecclesiastical writers-we have felt compelled to give this catalogue in order that we might be able to know both these works and those that are cited by the heretics under the name of the apostles, including, for instance, such books as the Gospels of Peter, of Thomas, of Matthias, or of any others besides them, and the Acts of Andrew and John and the other apostles, which no one belonging to the succession of ecclesiastical writers has deemed worthy of mention in his writings. And further, the character of the style is at variance with apostolic usage, and both the thoughts and the purpose of the things that are related in them are so completely out of accord with true orthodoxy that they clearly show themselves to be the fictions of heretics. Wherefore they are not to be placed even among the rejected writings, but are all of them to be cast aside as absurd and impious.
Eusebius, the Church History 3:25
Eusebius divided New Testament books into three categories: accepted, disputed and rejected. The accepted books consist of four gospels, Acts, Paul epistles (how many and whether they include Hebrews are not specified), 1 John, 1 Peter and Apocalypse of John (or Revelation). Disputed books include James, Jude, 2 Peter, 2 & 3 John and Gospel according to Hebrews; while books like Acts of Paul, Apocalypse of Peter, Shepherd of Hermas, Epistle of Barnabas, Didache, but also Revelation belong to rejected books. Note that Revelation was listed as both accepted and rejected books. It shows the two different opinions of the canonicity of Revelation, which was especially true among the eastern churches. Eusebius also mentioned Gospel of Thomas, Gospel of Matthias and a number of Acts bearing names of some apostles. According to him those books cannot even be considered as rejected books but must be cast aside.