m. But he also suggests that it may be derived from the
name of Avalloc, living there with his daughters. Avalloc is evidently
the "Rex Avallon" (Avallach) to whose palace Arthur was carried and
healed by the _regia virgo_.[1254] He may therefore have been a mythic
lord of Elysium, and his daughters would correspond to the maidens of
the isle. William also derives "Glastonbury" from the name of an
eponymous founder Glastenig, or from its native name _Ynesuuitron_,
"Glass Island." This name reappears in Chretien's _Eric_ in the form
"l'isle de verre." Giraldus explains the name from the glassy waters
around Glastonbury, but it may be an early name of Elysium.[1255] Glass
must have appealed to the imagination of Celt, Teuton, and Slav, for we
hear of Merlin's glass house, a glass fort discovered by Arthur, a glass
tower attacked by the Milesians, Etain's glass _grianan_, and a boat of
glass which conveyed Connla to Elysium. In Teutonic and Slavonic myth
and _Maerchen_, glass mountains, on which dwell mysterious personages,
frequently occur.

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 _sid_ was a continuation of this belief,
but now the _sid_ 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
co