"her Gretchen yellow hair"

Gretchen, or Margarete, is the chief female protagonist of Faust, a tragedy by Johann Wolfgang von Goethe.  She is a beautiful, blonde girl who Faust sees upon the street; having sold his soul to the devil in return for pleasure on earth, he demands that she be delivered to him.  She is innocent, but falls in love with Faust and agrees to lie with him.  He gives her sleeping potion to silence her mother but it turns out to be poison; when Gretchen also becomes pregnant, her brother challenges Faust to a duel but is killed.  Her tragedy reaches its climax when she drowns her newborn child and is sentenced to death, but at last she sees Faust's true nature, rejects him, and is saved by heavenly voices.  The character of Gretchen was modelled on Friederike Brion, a parson's daughter who had a short but intense love affair with the young Goethe.

There are many parallels between Gretchen and Mignon.  Both are innocents who lose loved ones and suffer at the hands of deceitful men.  A selection of text relating to Gretchen from Goethe's work, known as Gretchen am Spinnrade (Gretchen at the Spinning Wheel) was the first successful lied written by Franz Schubert in 1818; Mignon has now become closely associated with Schubert's songs for the female voice.  Gretchen's story ends with her salvation through heavenly voices, singing above; Mignon is similarly saved through music in her alliance with the Princess and the Maestro in Transbaikalia.