In ancient writers there is no information as to the views prevalent among the Celts regarding the forms or the abodes of the spirits of the dead, beyond the statement that the Druids taught the doctrine of their re-birth.

We are thus compelled to look to the evidence afforded by myth, legend, and folk-lore.

These give fair indications as to the types of earlier popular belief in these matters, but it would be a mistake to assume that the ideas embodied in them had remained entirely unchanged from remote times.

The mind of man at certain levels is quite capable of evolving new myths and fresh folk-lore along the lines of its own psychology and its own logic.

The forms which the soul could take doubtless varied greatly in men's opinions in different districts and in different mental perspectives, but folk-lore tends to confirm the view that early man, in the Celtic world as elsewhere, tended to emphasise his conception of the subtlety and mobility of the soul as contrasted with the body.