The Music of the Planets by Kepler

Kepler's first law of planetary motion is that the planet will move proportionately faster as it comes closer to the sun, and slow down when farther away. He even includes musical notation where individual notes written on a staff are labelled with the names of the planets. And says that different singing voices correlate to different heavenly bodies. If you are a tenor, for instance, then you have a martian singing voice since its place on the harmonic scale is like that of mars relative to the other planets.