probably wrote about A.D. 130, and collected his materials many years earlier, also quoted that Epistle, as we learn from Eusebius. Now, the connection between the Gospel and the Epistle is, as has been cleverly remarked, like the connection between a star and its satellite. They are obviously the work of the same author. If Polycarp, who had himself seen St. John, knew that the Epistle was genuine, he must have known that the Gospel was genuine. The evidence which can definitely be dated between A.D. 120 and A.D. 170 is of extreme interest. It proves conclusively that a belief in the authenticity of this Gospel was so firmly engrained in the Christian mind that men holding the most opposite opinions appealed to its authority. It is true that the "irrational" Alogi rejected it, and that Marcion repudiated it, not because it was not by an apostle, but because St. Paul was the only apostle whom he admired. But it was used by the Catholics, the Gnostics, and the Montanists. St. Justin Martyr was acquainted with it, and before he wrote, Basilides, the great Gnostic of Alexandria, borrowed from it some materials for his doctrine. The equally celebrated Gnostic Valentinus used it, and his followers also revered it. About A.D. 170 Heracleon, an eminent Valentinian, wrote a commentary upon this Gospel, of which commentary some fragments still remain. The Montanists arose in Phrygia about A.D. 157. Montanus, their founder, endeavoured to revive the power of prophecy, and his followers maintained that "the Paraclete said more things in Montanus than Christ {87} uttered in the Gospel." It can easily be proved that their teaching was an attempt to realize some of the promises of our Lord contained in St. John's Gospel. And the fact that the Montanists were strongly opposed to the Gnostics makes it all the more remarkable that both sects regarded this Gospel as so important. Somewhat before A.D. 170 St. John's Gospel was inserted by the great Syrian apologist, Tatian, in his _Diatessaron_, or harmony of the Gospels, and the apocryphal Acts of John composed near the same date contain unmistakable allusions to this Gospel.