Sooner or later the primitive philosopher was bound to consider whither the soul went in dreams or in death.

He may not at first have thought of any other sphere than that of his own normal life, but other questions, such as the home of the spirits of vegetation in or under the earth, would suggest, even if this thought had not occurred to him before, that the spirits of men, too, had entrance to the world below.

Whether this world was further pictured in imagination depended largely on the poetic genius of any given people.

The folk-lore of the Celtic races bears abundant testimony to their belief that beneath this world there was another.

The 'annwfn' of the Welsh was distinctly conceived in the folk-lore embodied in mediaeval poetry as being 'is elfydd' (beneath the world).