The third century saw the first attempt to discredit millenarianism, when Origen, perhaps the most influential of all the theologians of the ancient Church, began to present the Kingdom as an event which would take place not in space or time but only in the souls of believers. For a collective, millenarian eschatology Origen substituted an eschatology of the individual soul. What stirred his profoundly Hellenic imagination was the prospect of spiritual progress begun in this world and continued in the next; and to this theme theologians were henceforth to give increasing attention. . . .  When in the fourth century Christianity attained a position of supremacy in the Mediterranean world and became the official religion of the Empire, ecclesiastical disapproval of millenarianism became emphatic. The Catholic Church was now a powerful and prosperous institution, functioning according to a well-established routine; and the men responsible for governing it had no wish to see Christians clinging to out-dated and inappropriate dreams of a new earthly Paradise. Early in the fifth century St Augustine propounded the doctrine which the new conditions demanded. According to The City of God the Book of Revelation was to be understood as a spiritual allegory; as for the Millennium, that had begun with the birth of Christianity and was fully realized in the Church. This at once became orthodox doctrine. - Norman Cohn, The Pursuit of the Millennium: Revolutionary Millenarians and Mystical Anarchists of the Middle Ages