Harmonies of the World by Johannes Kepler tr. by Charles Glenn Wallis [1939]

Johannes Kepler, who originally studied theology, was introduced to the Copernican world-view while studying for his Master's degree in Philosophy at the University of Tübingen. He wrote a paper attempting to reconcile the Copernican system with the Bible. Although he wanted to enter the ministry, he was offered a chair of astronomy at the Lutheran school of Graz, which he accepted.

He became convinced that there was a relationship between the five regular solids and the structure of the known solar system. His first work on Astronomy, Precursor of Cosmographic Dissertations or the Cosmographic Mystery, published in 1596, brought him to the attention of Tycho Brahe and Galileo. Banished from his homeland by an edict against Protestants in 1598, Kepler eventually ended up in Prague, where he worked under Tycho. On Tycho's death, Kepler took over his post and inherited Tycho's massive archive of observations.

Johannes Kepler published Harmonies of the World in 1619. This was the summation of his theories about celestial correspondences, and ties together the ratios of the planetary orbits, musical theory, and the Platonic solids. Kepler's speculations are long discredited. However, this work stands as a bridge between the Hermetic philosophy of the Renaissance, which sought systems of symbolic correspondences in the fabric of nature, and modern science. And today, we finally have heard the music of the spheres: data from outer system probes have been translated into acoustic form, and we can listen to strange clicks and moans from Jupiter's magnetosphere.

Towards the end of Harmonies Kepler expressed a startling idea,--one which Giordiano Bruno had been persecuted for, two decades before--the plurality of inhabited worlds. He muses on the diversity of life on Earth, and how it was inconceivable that the other planets would be devoid of life, that God had "adorned[ed] the other globes too with their fitting creatures". [pp. 1084-1085]

Production Notes: this is an excerpt from the standard English edition of Kepler's works, which has been published in part and whole numerous times. Due to non-renewal, this text has fallen into the public domain in the US. The translator, Charles Glenn Wallis, is often uncredited, but if you see an English translation of this on the market, it will undoubtably be the Wallis translation. The particular copytext I used was the one published in volume 16 of The Great Books of the Western World; I have corrected minor spelling errors in the usual fashion.