Kepler’s Harmonices Mundi

In 1619 Johannes Kepler published Harmonices Mundi (The Harmony of the World). The book contains his definitive theory of the cosmos, blending a refined version of his original polyhedral theory with elliptic planetary orbits and the theory of musical harmony. Thanks to his harmonic –nowadays the third law of planetary motion– he succeeded in fulfilling the ancient dream of proving that the heavens resound (silently) to the same chord and scale structures as Western music. Kepler describes his cosmological theory “on the most perfect harmonies of the heavenly motions“ in Book V of the Harmonices Mundi (1619), after discussing the necessary geometric, harmonic, metaphysical and astrological prerequisites in Books I-IV. Book V opens with three chapters on his old polyhedral theory, developed 22 years earlier in the Mysterium Cosmographicum (1596). The remaining chapters combine this with his major astronomical achievements on elliptic planetary orbits, described in the Astronomia Nova (1609), and h