The origin of the Celtic Elysium belief may be found in universal myths of a golden age long ago in some distant Elysian region, where men had lived with the gods. Into that region brave mortals might still penetrate, though it was lost to mankind as a whole. In some mythologies this Elysium is the land whither men go after death. Possibly the Celtic myth of man's early intercourse with the gods in a lost region took two forms. In one it was a joyful subterranean region whither the Celt hoped to go after death. In the other it was not recoverable, nor was it the land of the dead, but favoured mortals might reach it in life. The Celtic Elysium belief, as known through the tales just cited, is always of this second kind. We surmise, however, that the land of the dead was a joyous underworld ruled over by a god of fertility and of the dead, and from that region men had originally come forth. The later association of gods with the _síd_ was a continuation of this belief, but now the _síd_ are certainly not a land of the dead, but Elysium pure and simple. There must therefore have been at an early period a tendency to distinguish between the happy region of the dead, and the distant Elysium, if the two were ever really connected. The subject is obscure, but it is not impossible that another origin of the Elysium idea may be found in the phenomenon of the setting sun: it suggested to the continental Celts that far off there was a divine land where the sun-god rested. When the Celts reached the coast this divine western land would necessarily be located in a far-off island, seen perhaps on the horizon. Hence it would also be regarded as connected with the sea-god, Manannan, or by whatsoever name he was called. The distant Elysium, whether on land or across the sea, was conceived in identical terms, and hence also whenever the hollow hills or _síd_ were regarded as an abode of the gods, they also were described just as Elysium was.