The spirit of the waters was often embodied in an animal, usually a fish.  Even now in Brittany the fairy dweller in a spring has the form of an eel, while in the seventeenth century Highland wells contained fish so sacred that no one dared to catch them.[616] In Wales S. Cybi’s well contained a huge eel in whose virtues the villagers believed, and terror prevailed when any one dared to take it from the water.  Two sacred fish still exist in a holy well at Nant Peris, and are replaced by others when they die, the dead fish being buried.[617] This latter act, solemnly performed, is a true sign of the divine or sacred character of the animal.  Many wells with sacred fish exist in Ireland, and the fish have usually some supernatural quality—­they never alter in size, they become invisible, or they take the form of beautiful women.[618] Any one destroying such fish was regarded as a sacrilegious person, and sometimes a hostile tribe killed and ate the sacred fish of a district invaded by them, just as Egyptians of one nome insulted those of another by killing their sacred animals.[619] In old Irish beliefs the salmon was the fish of knowledge.  Thus whoever ate the salmon of Connla’s well was dowered with the wisdom which had come to them through eating nuts from the hazels of knowledge around the well.  In this case the sacred fish was eaten, but probably by certain persons only—­those who had the right to do so.  Sinend, who went to seek inspiration from the well, probably by eating one of its salmon, was overwhelmed by its waters.  The legend of the salmon is perhaps based on old ritual practices of the occasional eating of a divine animal.  In other cases, legends of a miraculous supply of fish from sacred wells are perhaps later Christian traditions of former pagan beliefs or customs concerning magical methods of increasing a sacred or totem animal species, like those used in Central Australia and New Guinea.[620] The frog is sometimes the sacred animal, and this recalls the Maerchen of the Frog Bridegroom living in a well, who insisted on marrying the girl who drew its waters.  Though this tale is not peculiar to the Celts, it is not improbable that the divine animal guardian of a well may have become the hero of a folk-tale, especially as such wells were sometimes tabu to women.[621] A fly was the guardian spirit of S. Michael’s well in Banffshire.  Auguries regarding health were drawn from its movements, and it was believed that the fly, when it grew old, transmigrated into another.[622]

Such beliefs were not peculiarly Celtic.  They are found in all European folk-lore, and they are still alive among savages—­the animal being itself divine or the personification of a divinity.  A huge sacred eel was worshipped by the Fijians; in North America and elsewhere there were serpent guardians of the waters; and the Semites worshipped the fish of sacred wells as incarnations or symbols of a god.