The gnostic heresy, then, presents us with the first instance of a law which will run all through the Church’s history. Peter, the first Apostle, meets and refutes Simon Magus, the first propagator of falsehood, who receives divine sacraments and then claims against the giver to be “the great power of God.” This fact is likewise the symbol of a long line of action, wherein it is part of the divine plan to make the perpetual restlessness of error subserve the complete exhibition of truth. The Gnostics denied the divine monarchy; at once mutilated and misinterpreted Scripture; claimed to themselves a secret tradition of truth. We owe to them in consequence the treatises of Irenæus, Tertullian, and Clement, and a written exhibition of the Church’s divine order, succession, and unity, as well as a specific mention of the tie which held that unity together; and the mention of this tie at so early a period might otherwise have been wanting to us. But these three writers do but represent to us partially an universal result. The danger which from gnostic influence beset all the chief centres of ecclesiastical teaching marks the transition from the first state of simple faith to that of human learning, inquiry, and thought, turned upon the objects of Christian belief. The Gnostics had a merit which they little imagined for themselves. They formed the first doctors of post-apostolic times. Irenæus, Tertullian, and Clement are a great advance upon the more simple and external exhibition of Christianity which we find in the apologists. In them the Church is preparing to encounter the deepest questions moved against her by Greek philosophy. They are her first champions in that contest with Hellenic culture which was a real combat of mind, not a mere massacre of unresisting victims, and which lasted for five hundred years.