Sir Orfeo as being a parallel dimension to the everyday world rather than the Land of the Dead as in the Greek myth of Orpheus and Eurydice. The ability to move between one world and the other distinguishes the tale as told in its various British versions such as "Sir Orfeo" and the Shetland ballad "King Orfeo" where the captors are envisaged as inhabitants of a parallel fairy domain rather than as the infernal region of the Dead ruled over by Hades as in the Greek myth. Katharine Briggs sees the tale as related in British folk narratives as being equally influenced
Orpheus son of the Thracian king Oeagrus and the Muse Calliope. Greeks of the Classical age venerated Orpheus as the greatest of all poets and musicians; it was said that while Hermes had invented the lyre, Orpheus had perfected it. Poets such as Simonides of Ceos said that Orpheus' music and singing could charm the birds, fish and wild beasts, coax the trees and rocks into dance, and divert the course of rivers. Orpheus was one of the handful of Greek heroes to visit the Underworld and return; his music and song even had power over Hades. Some sources credit Orpheus