As Mr.Alfred Nutt points out, Irish legend seems to regard this re-birth only as the privilege of the truly great.

It is of interest to note the curious persistence of similar ideas as to death and the other-world in literature written even in Christian times and by monastic scribes.

In Welsh, in addition to Annwfn, a term which seems to mean the 'Not-world,' we have other names for the world below, such as 'anghar,' the loveless place; 'difant,' the unrimmed place (whence the modern Welsh word 'difancoll,' lost for ever); 'affwys,' the abyss; 'affan,' the land invisible.

The upper-world is sometimes called 'elfydd,' sometimes 'adfant,' the latter term meaning the place whose rim is turned back.
Apparently it implies a picture of the earth as a disc, whose rim or lip is curved back so as to prevent men from falling over into the 'difant,' or the rimless place.

In modern Celtic folk-lore the various local other- worlds are the abodes of fairies, and in these traditions there may possibly be, as Principal Rhys has suggested, some intermixture of reminiscences of the earlier inhabitants of the various districts.