Erlking captures the Romantic "strangeness and wonder" of Goethe's ballad. Erlking is based upon the legend that whoever is touched by the king of the elves must die.
Schubert used a triplet pattern to set up the eerie atmosphere of the poem. The image of a galloping horse and great urgency is seen through this triplet pattern. The use of the minor key also contributes to the atmosphere.
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Although only one singer is used, each of the four characters are portrayed differently. The narrator is in the middle range with less emotion. The father is sung in the low range and becomes a calming line. The son is in the high range with a great deal of dissonance, while the erlking is in the middle range, but using a major mode.
By changing the melody, harmony, rhythm, and accompaniment, Schubert was able to paint a picture of a child's terror by increasing the high range and clashing dissonance. The father's part has a more rounded vocal line, thus the calming effect. The erlking, or elf is seen as seductive by the use of smooth melodious phrases which at first are coaxing, then become insistent as the terror of the child increases.
The music follows the action of the narrative with a steady rise in tension and pitch that builds almost to the very end. As they draw closer to home, the constant triplet rhythm slows just as a rider and horse would do upon reaching the safety of home. Yet the last line: "In his arms the child" is drawn out by the use of a pause before the final two words: "was dead."