While all this repression was going on, the Church was making itself acceptable, just as the Mosaic system had done in its day, by assimilating the symbols of the forbidden faiths. Itself instituted without formularies or ceremonial, both were needed when it became a step-ladder of ambition and the expedient displacer of the corrupt idolatries into which sun-worship had disintegrated. Hence among the means of organization, observance and symbol took the place of original simplicity, and it is small wonder that ideas were adopted which were already in men's minds. Elements of heathenism which, after the lapse of centuries, still clung to the Church's robes, became an interwoven part of her dearest symbolism. If men did not burn what they had adored, they in effect adored that which they had burned. In spite, however, of edicts and adoptions, paganism has never been entirely rooted out; what Sismondi calls the "rights of long possession, the sacredness of time-hallowed opinion, and the potency of habit," are not yet entirely overcome in the midst of the most enlightened peoples. The carvings which point back to forgotten myths have their parallels in curious superstitions and odd customs which are not less venerable. There were many compromises made on account of the ineradicable attachment of the people to religious customs into which they were born. Christian festivals were erected on the dates of heathen observances. In the sixth century, Pope Gregory sent word to Augustine, then in England, that the idolatrous temples of the English need not be destroyed, though the idols should, and that the cattle sacrificed to the heathen deities should be killed on the anniversary of dedication or on the nativities of the saints whose relics were within the church. It is said that it was, later, usual to bring a fat buck into St. Paul's, London, with the hunters' horns blowing, in the midst of divine service, for the cathedral was built on or near the site of a former temple of Diana. This custom was made the condition of a feudal tenure. The story of Prosperine, another form of Diana, was the subject of heathen plays, and down to the sixteenth century the character appears in religious mystery plays as the recipient of much abuse.