speeds at the perihelion and aphelion) is very nearly equivalent to a consonant musical interval. Furthermore, the ratios between these extreme speeds of the planets compared against each other create even more mathematical harmonies. These speeds explain the eccentricity of the orbits of the planets in a natural way that appealed to Kepler's religious beliefs in a heavenly creator. While Kepler did believe that the harmony of the worlds was inaudible, he related the motions of the planets to musical concepts in book four of Harmonices. He makes an analogy between comparing the extreme speeds of one planet and the extreme speeds of multiple planets with the difference between monophonic and polyphonic music. Because planets with larger eccentricities have a greater variation in speed they produce more "notes." Earth's maximum and minimum speeds, for example, are in a ratio of roughly 16 to 15, or that of a semitone, whereas Venus' orbit is nearly circular, and therefore only produces a singular note. Mercury, which has the largest eccentricity, has the largest interval, a minor tenth, or a ratio of 12 to 5. This range, as well as the relative speeds between the planets, led Kepler to conclude that the Solar System was composed of two basses (Saturn and Jupiter), a tenor (Mars), two altos (Venus and Earth), and a soprano (Mercury), which had sung in "perfect concord," at the beginning of time, and could potentially arrange themselves to do so again. He was certain of the link between musical harmonies and the harmonies of the heavens and believed that "man, the imitator of the Creator," had emulated the polyphony of the heavens so as to enjoy "the continuous duration of the time of the world in a fraction of an hour." Kepler was so convinced of a creator that he was convinced of the existence of this harmony despite a number of inaccuracies present in Harmonices. Many of the ratios differed by an error greater than simple measurement error from the true value for the interval, and the ratio between Mars' and Jupiter's angular velocities does not create a consonant interval, though every other combination of planets does. Kepler brushed aside this problem by making the argument, with the math to support it, that because these elliptical paths had to fit into the regular solids described in Mysterium the values for both the dimensions of the solids and the angular