After the addition of Mark to Matthew it was comparatively easy to take in Luke-Acts as a third, and to form composites out of the three such as the _Gospel of Peter_ (North Syria _c._ 130) and the _Gospel of the Nazarenes_ (Coele-Syria _c._ 140). Justin at Rome (_c._ 153) is still such a three-gospel man, though affected by the Fourth; whereas his predecessor Hermas (125-140) seems to rest on Mark alone, though perhaps acquainted with Matthew. The step was a harder one which aimed to take in the Fourth gospel. Tatian at Rome (_c._ 175) and Theophilus at Antioch (181) are the agents of its accomplishment; and, as we have seen, it was not effected without a determined opposition, led at Rome by the presbyter Gaius, and answered by Irenæus (_c._ 186) and Hippolytus (_c._ 215). Such opposition from the side of advocates of Petrine apostolicity is anticipated in the most significant and important of all the epilogues, the so-called Appendix or Epilogue to the Fourth gospel (John xxi.). Just when, or where, this supplement was added is one of the most difficult problems of the higher criticism. On the side of external evidence we have the fact that it shows no effect in Mark xvi. 9-21, where John xx. is employed, and that there is a great change about A.D. 170 in the treatment of this Gospel and its related Epistles, those who use them before this time showing no disposition to treat them as having high apostolic authority. On the side of internal evidence there are such data as the use of the second-century name for the Sea of Galilee ("Sea of Tiberias," xxi. 1), and references to the martyrdom of Peter at Rome (xxi. 18 f.) and to legends of John as the 'witness' who should survive until the Coming (xxi. 23). Whether these data suggest an origin at Ephesus, or at Rome, and at just what date, are problems for technical research. That which is of chief interest for us is the motive and function of this supplement to the Ephesian Gospel, and the light it throws upon conditions in the church at large.