Das Lied von der Erde
The timeless, meditative closing bars of Gustav Mahler’s song “Abschied” from "Das Lied von der Erde" (1909) fully exploit the expressive power and ambiguity of the sixth chord. “The final sonority, the famous added-sixth chord, is particularly ingenious... because it fuses the two principal keys of "Das Lied" (A minor and C major).”