Embryogeny of Christianity, if one may so express it, ends about the death of Marcus Aurelius in 180. At this date the child has all its organs; it is sundered from its mother; henceforward it will live its own life. The death of Marcus Aurelius, moreover, can be considered as marking the close of ancient civilisation. What of excellence is achieved after this is no longer achieved by the hellenic-roman principle; the judeo-syrian principle wins the day, and, although more than a hundred years are to elapse before its complete triumph, there is already no doubt that to it belongs the future. The third century is the death agony of a world which, in the second, has still been full of life and strength.