The Instrumentum Johanneum

In the age of Tertullian and Hippolytus the Instrumentum-Johanneum was a unit. For the Church at large all five of the disputed books stood or fell together. Hence if testimony from Papias were lacking in behalf of the Gospel (and we have seen that none is likely to have been available) his testimony to the Revelation could be made to serve as well. If a Hippolytus in defending the authenticity of the Revelation against Gaius, quoted Melito, Irenaeus or Methodius; or if in his treatise Against Marcion he spoke of Papias as having borne witness to the "credibility" of Rev. 1 9— 11 this would easily be construed by the writer of any third-century Prologue as applicable to the whole Instrumentum Johanneum. [Benjamin Bacon, Studies in Matthew p. 455]