 Close work with observational data collected by Tycho Brahe led Kepler to abandon the universal ancient view that the orbits of the planets were circular and to recognize their elliptical nature. More clearly Pythagorean is Kepler’s consistent belief that the data show that the motions of the planets correspond in various ways to the ratios governing the musical concords (see Dreyer 1953, 405–410), so that there is a heavenly music, a doctrine attested for Philolaus and Archytas, which probably goes back to Pythagoras as well. For Kepler, however, the music produced by the heavenly motions was “perceived by reason, and not expressed in sound” (Harmonice Mundi V 7). In his attempt to make the numbers of the heavenly music work, he joked that he would appeal to the shade of Pythagoras for aid, “unless the soul of Pythagoras has migrated into mine” (Koestler 1959, 277).