mediaeval fairy-lore; and the early Celtic literature, although its study,
complicated by an unfamiliar language, has only recently been undertaken
scientifically, has already revealed an extremely rich and complete store
of romance that extends over a thousand years. From manuscripts which are
attributed to the twelfth century (and even so contain matter rightly
belonging to the ninth or tenth), we can trace the development of a creed
concerning supernatural beings through the succeeding centuries, down to a
time at which the written account is displaced by recorded oral tradition.
A race of beings, who must originally have fallen from the Celtic Olympus,
continue to appear, with characteristics that remain the same in essence,
and under a designation that may be heard in Ireland today, through ten
centuries of Irish tradition and literature.[76]

These people are called in Irish mythology the _Tuatha Dé Danann_,
described from at latest 1100 A.D. as _aes sidhe_, "the folk of the
[fairy-] hillock;" the name for fairies in Ireland now is "the Sidhe."[77]
Originally, it may be, the _aes sidhe_ were not identified with the _Tuatha
Dé Danann_; and before the twelfth century the Sidhe were not associated
with the Celtic belief in "a beautiful country beyond the sea," a happy
land called by various names--Tir-nan-Og (the land of youth), Tir Tairngire
(the land of promise)--which has now become "fairy-land." In the earliest
heroic legends the _Tuatha Dé Danann_ assist or protect mortal champions,
and fall in love with mortal men and maids; but with the spread of
Christianity (as might be expected) they lost many of their previous
characteristics.[78]

To look back for a moment, we must note that so far we have touched no
belief later than the fifteenth century, and already we have seen enough
blending of various superstitions and legends to give our fairies a very
mixed ancestry. Classical mythology, Celtic heroic sagas and northern Eddas