Die Harmonie der Welt (The Harmony of the World) is an opera in five acts by Paul Hindemith. The German libretto was by the composer. The title of the opera is taken from Harmonices Mundi by the astronomer Johannes Kepler (1571–1630) who is the subject of the opera. Hindemith used the planetary system as a metaphor for his own musical arrangement of the chromatic scale. The opera was completed in May 1957. Hindemith had previously composed a symphony of the same name in 1951.