All changes in popular belief have been, and, practically, remain superficial; the old animism pervades the higher creeds. In our own island, for example, the Celtic and pre-Celtic paganism remained unleavened by the old Roman religion. The legions took back to Rome the gods which they brought with them. The names of Mithra and Serapis occur on numerous tablets, the worship of the one--that "Sol invictus" whose birthday at the winter solstice became (see p. 42) the anniversary of the birth of Christ--had ranged as far west as South Wales and Northumberland; while the foundations of a temple to the other have been unearthed at York. The chief Celtic gods, in virtue of common attributes as elemental nature-deities, were identified with certain _dii majores_ of the Roman pantheon, and the _deae matres_ equated with the gracious or malevolent spirits of the indigenous faith. But the old names were not displaced. Neither did the earlier Christian missionaries effect any organic change in popular beliefs, while, during the submergence of Christianity under waves of barbaric invasion, there were infused into the old religion kindred elements from oversea which gave it yet more vigorous life. The eagle penetration of Gibbon detected this persistent element at work when he described the sequel to the futile efforts of Theodosius to extirpate paganism. The ancestor worship which lay at the core of much of it took shape among the Christianized pagans in the worship of martyrs and in the scramble after their relics. The bodies of prophets and apostles were discovered by the strangest coincidences, and transported to the churches by the Tiber and the Bosphorus, and although the supply of these more important remains was soon exhausted, there was no limit to the production of relics of their person or belongings, as of filings from the chains of S. Peter, and from the gridiron of S. Lawrence. The catacombs yielded any number of the bodies of martyrs, and Rome became a huge manufactory to meet the demands for wonder-working relics from every part of Christendom. A sceptical feeling might be aroused at the claims of a dozen abbeys to possession of the veritable crown of thorns wherewith the majesty of the suffering Christ was mocked, but it was silenced before the numerous fragments of his cross, since ingenuity has computed that this must have contained at least one hundred and eighty million cubic millemetres, whereas the total cubic volume of all the known relics is but five millions. "It must," remarks Gibbon (Decline and Fall, end of chap. xxviii), "ingeniously be confessed that the ministers of the Catholic Church imitated the profane model which they were impotent to destroy. The most respectable bishops had persuaded themselves that the ignorant rustics would more cheerfully renounce the superstitions of paganism if they found some resemblance, some compensation, in the bosom of Christianity. The religion of