A distinguished leader of the Gnostics was _Valentinus_, who came to Rome about A.D. 140, and continued there till the time of Anicetus. His testimony and that of his followers is, if possible, more weighty than even that of Marcion. His method, according to the testimony of Tertullian, was not to reject and mutilate the Scriptures, but to pervert their meaning by false interpretations. Tertullian says, Against Heretics, ch. 38: "For though Valentinus seems to use the entire instrument, he has done violence to the truth with a more artful mind than Marcion." "The entire instrument"--Latin, _integro instrumento_--includes our four canonical gospels. Clement of Alexandria and Hippolytus have preserved quotations from Valentinus in which he refers to the gospels of Matthew, Luke, and John. See Westcott, Canon of the New Testament, 4. 5. Respecting the gospel of John in particular, Irenaeus says, Against Heresies, 3. 11, that "the Valentinians make the most abundant use of it." Heracleon, whom Origen represents as having been a familiar friend of Valentinus, wrote a commentary on John, from which Origen frequently quotes; but if Valentinus and his followers, in the second quarter of the second century, used "the entire instrument," they must have found its apostolic authority established upon a firm foundation before their day. This carries us back to the age immediately succeeding that of the apostles, when Polycarp and others who had known them personally were yet living. The testimony of the Valentinians, then, is of the most decisive character. Another prominent man among the heretical writers was _Tatian_, a contemporary and pupil of Justin Martyr, who, according to the testimony of Eusebius, Epiphanius, and Theodoret, composed a _Diatessaron_, that is, a _four-fold gospel_; which can be understood only as a harmony of the four gospels which, as has been shown, were used by Justin; or of such parts of these gospels as suited his purpose; for Tatian, like Marcion, omitted all that relates to our Lord's human descent. With this Diatessaron, Theodoret was well acquainted; for he found among his churches more than two hundred copies, which he caused to be removed, and their places supplied by the four canonical gospels. As to other gospels of the second century, which are occasionally mentioned by later writers, as "The Gospel of Truth," "The Gospel of Basilides," etc., there is no evidence that they professed to be connected histories of our Lord's life and teachings. They were rather, as Norton has shown, Genuineness of the Gospels, vol. 3, chap. 4, doctrinal works embodying the views of the sectaries that used them.