The closest thing my dad ever had to a bible was a video set to the 1980 television series Cosmos: A Personal Voyage. I spent many of my formative days watching it with him, even though the show is widely forgotten and feels dated. Cosmos starred astronomer Carl Sagan, whose popularity as a public advocate for science and science education endured until his death in 1996. Sagan famously organized and disseminated the first picture of Earth as a “pale blue dot”, captured by Voyager 1 as it flew by Saturn on its way out of the solar system.
But in thinking about this issue’s theme, I’ve found Sagan’s teachings strangely irritating and unhelpful. I can’t think of the word “horoscopes” without Sagan interdicting, “the pseudoscience of astrology”, straight out of the third chapter of Cosmos. Astrophysics treats astrology like a vestigial limb, an appendix on the body of natural science.
I also can’t stop myself from giving in to Sagan’s gospel. There’s no overcoming the rapture of his mellifluous prose. In the opening credits Sagan, like a modern bard, recites:
There are two ways to view the stars:
as they really are
and as we might wish them to be...
Sagan begins the lesson with conflicting descriptions of Jupiter, Saturn, and Mars: a scientific account of each planet’s physical properties and a pseudoscientific account of their supposed astrological properties. As he moves between the descriptions, ominous harpsichord music marks his transitions between “Jupiter’s regal bearing and a gentle disposition,” “Saturn, the gravedigger, fostering mistrust, suspicion and evil,” and “Mars, the warrior, instigator of quarrels, violence and destruction.”
At its essence, astrology is the process of committing the stars to prescribed discourse. The Greeks had twelve constellations of stars that give us the twelve signs of the zodiac. As the stars in the night skies changed with the seasons and the earth revolved around the sun, there was a tale for the apparent life and death of every constellation. In Greek, “Zodiac” means “lifebelt”, because ancient astronomers realized that the planets had irregular orbits, and followed the same path as the Sun and the Moon. In other words, these were visual manifestations of the Gods, the heavenly bodies closest to us.
Today astronomers refer to the “lifebelt,” as the ‘ecliptic’ — the common path taken by the sun, moon, and planets around our own. The zodiac constellations form our interstellar frame of reference, delimiting the natural horizon of our observable world. When the Greeks looked up at the sky, they knew the constellations and the stars as part of their culture. They would have known every constellation’s myth. How many constellations can you name?
Astronomers and astrologers were not always so distinct.
For most of human history the one encompassed the other.
But there came a time when astronomy escaped from the confines of astrology.
The two traditions began to diverge in the life and mind of Johannes Kepler.
It was he who demystified the heavens by discovering that a physical force lay behind the motions of the planets.
He was the first astrophysicist and the last scientific astrologer…
Sagan records Kepler’s role as the first astrophysicist, but I’m more interested his role as the last astrologer — the Kepler who obsessed over horoscopes, the music of the spheres, and matters of the soul.
Kepler was a product of the Protestant Reformation, a free thinker endowed with a tremendous intellect. He was deeply influenced by his German liberal arts education, where he saw himself in dialogue with Aristotle on the ideas of Metaphysics. He was a virtuous mathematician whose method followed the God-given natural light of reason. This track would lead him to discover three distinct laws of planetary motion, which served to confirm his belief in a divine order, but for us they are the first laws of astronomy.
The proof and derivation for the third law occurs in his final work, Harmonices Mundi (1619), which was written after his major discoveries and ten years before his death. Ironically, this work includes little of scientific value aside from the few pages proving and deriving the last law of planetary motion. Most of it deals with the interrelation of geometric solids, musical harmonics, and planetary orbits. Harmony of the Worlds presents a comprehensive example of Kepler’s “celestial physics”.
His introduction to this work makes such a prescient proclamation that it still shakes the foundations of both religion and science:
I am free to give myself up to the sacred madness,
I am free to taunt mortals with the frank confession that I am stealing the golden vessels of the Egyptians, in order to build of them a temple for my God, far from the territory of Egypt.
If you pardon me, I shall rejoice; if you are enraged, I shall bear up.
The die is cast, and I am writing the book—whether to be read by my contemporaries or by posterity matters not. Let it await its reader for a hundred years, if God Himself has been ready for His contemplator for six thousand years.
In 1619 Kepler believed that he had finally found the true nature behind God’s universal plan: a unified field theory for connecting each of the elements of his natural philosophy—perfect polyhedrae, planetary rotations, and musical harmonics. Kepler’s theory fused divine mathematics and observation as proof of the perfect intelligence of His divine architecture. Historically, Kepler's work is a beautiful example of the Reformation’s integration of humanist philosophical texts with the development of modern scientific reason.
The last chapter of Harmonices Mundi departs from the rest of the book’s subject matter. In it, Kepler considers the sun under Plato’s division of higher knowledge, between noesis, directly intuiting an idea, and dianoia, discursively mediating concepts. For Kepler the sun was the highest form of knowing, noetic, because all minds come from and return to the sun. The planets in turn are dependent upon their relation, dianoia, mediated by the sun.
He has placed His tabernacle in the sun, the curia, palace, and praetorium or throne-room of the whole realm of nature are in the sun whatsoever chancellors, palatines, prefects the Creator has given to nature: for them, whether created immediately from the beginning or to be transported hither at some time, has He made ready those seats.
The book closes with Kepler entertaining various possibilities on the habitability of “other globes” and questioning how only a single planet could hold life.
Kepler’s revolutionary insight may have definitively set in motion the age of modernity, but he spent half his life making horoscopes trying to predict the future of his soul. Would God admit his soul through the gates of Heaven? Horoscopes, or the condition of his soul, didn’t stop Kepler from constructing the best models or from retiring an idea that didn’t fit the data. On the contrary, his earlier work was driven by self-torment, by the imperfection of his own work, and by his unworthiness before God. By the end, no doubt Kepler thought he had understood God’s plan, his intelligence, better than anyone before.
We freely inquire by natural reasons what sort of thing each mind is, especially if in the heart of the world there is a mind bound rather closely to the nature of things and performing the function of the soul of the world—or if also some intelligent creatures, of a nature different from human perchance do inhabit or will inhabit the globe thus animated