In 1618, Johannes Kepler published his last major work, the Harmonice Mundi (The Harmony of the World). The poverty, prosecution, and ostracism that he had experienced in his lifetime had left him bitter and pessimistic. He had become convinced that the earth was a celestial ball of everlasting misfortune. In a footnote to the Harmonice Mundi, he wrote: "The Earth sings Mi-Fa-Mi, so we can gather even from this that Misery and Famine reign on our habitat.”
Kepler made this comment not just because of the sense of doom and gloom which was pervading his mind during the final years of his life—he actually believed that the speed at which the planets move through space was proportional to certain notes of the Latinate musical scale popular in his day: do, re, mi, fa, sol, la, ti, do. He surmised that the sound of a planet corresponded to the character of life that it supported, and that the earth’s notes were mi-fa-mi.