A musician tuning its instrument before the rehearsal of "Das Rheingold."

"In the case of the Ring Cycle, the main sources are anonymous, Nordic, and German, possible compiled in 13th century, such as Edda, the primordial book of Icelandic mythology; or Volsunga Saga, also originated in Iceland in the 1300s. The name 'volsunga' (Wälsung) appears in The Valkyrie, but Wagner take from the book much more than only the name." (Perpetuo)