Changeling from a Drowned Country

In an anecdote of Colum Cille in "Sancti Columbae Hiensis cum Mongano Heroe Colloquium" (ed. Grossjean), a mysterious youth appears from his own experience. The youth describes the prosperous country which the lake has covered, and says that he has at various times been a deer, a salmon, a seal, a wolf, and a man. Carney: "The mysterious youth came to be identified with Mongan mac Fiachna, but I would suggest tentatively that in the original composer's mind, although preserved without identification, he probably came out of the water and may have been a manifestation of Manannan Mac Lir.