That Siegfried and Brunhild are at the end mythical, rather than at all historical, has been surmised, rather than proved. It has been attempted, in point of fact, to show that the whole story has arisen in its earliest form through a union of an old myth of Siegfried with the historical materials that have been indicated and others whose real significance has subsequently been obliterated and lost. The believers of this theory have pointed to the thoroughly mythical character of the version of the story in the "Edda" and particularly of its earliest part as plausible evidence, and they would see in the whole the union of a Frankish myth of Siegfried, originally independent, with a Burgundian historical narrative. Siegfried and Brunhild, in this way, have been thought to embody, at the beginning, the nature-myth of the awakening earth-goddess from the sleep of winter at the reanimating touch of summer. Lachmann makes the fundamental fact at the outset a myth of the death of Balder, and Wilhelm Müller a myth of Freyr, both light-gods of the old mythology. It is, nevertheless, impossible to follow the upholders of these theories into the details of their interpretation, and the whole main assumption of a mythical origin is a matter of doubt. That Siegfried and Brunhild, however, have mythical characteristics that they have retained after all memory of the ancient mythology as such has been absolutely forgotten, no reader of the story can deny, and in this respect the "Nibelungenlied" is no different from the legendary literature of all the nations of the world. Early German poems on the story of the Nibelungs, although it is altogether likely that they once existed, have not been preserved. The "Nibelungenlied" itself it is not possible to follow back of the twelfth century, by the middle of which it seems to have already had the form in which it has come down to us. The internal evidence of metre, rhyme, and language shows, too, beyond a doubt, that it could not have arisen at a much earlier time.