So much for the north: while on the east the Persian empire, hereditary foe of the Roman name, had found a new and more vigorous master in the race of the Sassanidæ, who took the religion of Zoroaster to reanimate the national spirit. Ardeschir claimed once more the whole realm which Cyrus and Darius had ruled. Henceforth the Romans had a neighbour more than ever threatening their eastern frontier, and never to be wholly subdued, until the empire of Mohammed arose to detach a great part of their dominion, and to move with redoubled force upon what remained. To the south of the Roman provinces in Africa were tribes at least as savage as those of the north. Thus the whole empire was enringed with enemies: on the east an opposing civilisation and religion; on the north and south barbarian tribes in perpetual confusion and conflict with each other. Such was the great realm of disorder which surged and heaved to the north and south of the empire; and such the second great enemy which in future times was to occupy the Christian Church, and at present offered the strongest contrast to that moral polity of peace and goodwill, of loyal submission, patient endurance, and heroic fortitude, which was spreading daily in the empire. 3. But there was yet another enemy within the empire itself, which from the beginning tracked the footsteps of the Church, grew with its increase, and everywhere attempted to dissolve its organisation and weaken its influence. The whole second century is occupied with the rise and tangled growth of the Gnostic sects. But these were not alone. From the very time of the Apostles we find the evidence of a number of sects, rising and falling, preying on and devouring each other, none without some portion of Christian truth, on which it feeds, blended with Jewish, Greek, Oriental, Egyptian, Libyan notions, prejudices, and errors; domiciled in various parts of the empire in accordance with the national or local character which they represent. They reproduce with a Christian colour the sects and the sect-life of the Greek schools of philosophy. As the wheat has its proper weed, which springs up in the midst of it and counterfeits it, so error, everywhere gathering round some portion of truth, forms itself into an antagonistic life. The force and truth of the Christian Church were shown not in the absence of these rivals, but in its triumph over their variety, in its remaining one whilst they diverged endlessly from that unchanging original type, in its continuous and uniform growth whilst they rose and fell, domineered in certain times and places, and then disappeared. In this its course the Church had to master very great difficulties, which were inherent in the manner of its rise. It had to remain one society in spite of the isolation and self-government of its local portions. It possessed in each place but a feeble minority of members compared with the mass of unbelievers. Against its assimilating