Kepler's Witch (12 page)

After Sebald's funeral, Kepler traveled on to Tübingen to speak with Mästlin face-to-face. Mästlin was generally happy with the book, though he had reservations about Kepler's introduction of an
anima movens,
a spirit of movement, or a force, in the sun. He worried that this blurred the line between astronomy and physics. Traditionally, astronomy was about geometry, about creating hypotheses that accounted for the appearances, for what people saw in the sky, while physics was about explaining movement on earth or in the atmosphere just above the earth, in the world under the sphere of the moon. Explaining the heavens in terms of earthly motion, that is, in terms of Aristotle's four causes, blurred the line in a suspicious way. What Mästlin did not realize, as twenty-first-century people do, is that this one idea was a watershed, a turning point in science leading to the modern world. Kepler's
anima movens
eventually became Newton's law of gravity, one of the grounding pillars of science.

Kepler's response to Mästlin, however, was more metaphysical than physical. “Of all the bodies in the universe,” he wrote, “the most excellent is the sun, whose whole essence is nothing else but the purest light. Than it there is no greater star; singly and alone it is the producer, conserver, and warmer of all things. It is a fountain of light, rich in fruitful heat, most fair, limpid, and pure to the sight. It is the source of vision and the portrayer of all colours, though itself devoid of colour.”
⁷
The sun was like God the Father, who created the universe. The stars were like God the Son, forever constant. The space between, the space of the moon and the planets, was like the Holy Spirit, the upholder and conserver of all things.

In spite of his concerns over some of Kepler's ideas, Mästlin applied to the Senate of Tübingen for approval of the book, the first necessary step for publication. The Senate's response was tepid. They recognized the young man's obvious talent, and they trusted Mästlin's word about its scientific value. Still, they worried about Kepler's attempts to reconcile
Copernicus with the Bible. How could anyone accept both the descriptions of creation in Genesis and a moving earth at the same time? Moreover, the book of Joshua clearly stated that the sun stopped moving in its course for fifteen minutes in order to give Israel the victory in battle. A moving earth simply did not make sense. Also, they worried that the average reader, who did not have Kepler's knowledge of Copernicus, could be led astray, and they wanted him to write a series of elucidations to explain the most difficult Copernican ideas to the newcomer.

In spite of the Senate's concerns, however, Kepler had become a minor celebrity in Tübingen. His discovery had made the rounds, and the same faculty who had fretted about him while he was a student celebrated him now that he had become an author. No one had yet come up with a scheme to calculate the number of the planets, their arrangement, and the size of their orbits or to add to that an explanation of their motion through the sky. The idea of an
a priori
cosmography, what moderns might call a theoretical cosmology, was entirely new. To tease out the thoughts of the Creator in pure mathematics was audacious, brilliant, and wonderful. After a dinner party, Martin Crucius, Kepler's old classics teacher, wrote a note about him in his otherwise pedestrian journal:
“Pulcher iuvenis,”
he said, “Charming boy!”
⁸

Meanwhile, Kepler traveled on to Stuttgart, where he joined the ranks of the lower and middle managers of the duchy in the
Trippeltisch,
the place in the ducal castle where such managers resided and ate their meals. While there, he petitioned the duke to have a model of his cosmography fashioned by a local goldsmith. He envisioned a goblet about the size of a drinking cup with the various Platonic solids—all hollow—nested inside one another like a matrushka. This idea caught the duke's imagination and he commissioned it at once, but the artisan he chose to do the job was slow and not all that excited about the goblet, so the project seemed to drag on forever. Meanwhile, Mästlin had continuing trouble negotiating with the Senate, and then with the publisher about who would pay for what, how it would be paid, and this, that, and the other. Because of these delays, Kepler stayed on in the duchy for nearly seven months, even though his leave of absence from the school was for no more than two.

The
Mysterium Cosmographicum
finally came out in December 1596, and by February 1597 Kepler had returned home and had found out the awful truth—while he was away, he let his bride slip through his fingers. He shouldn't have been away so long. What does it say about the ardor of a suitor who is off traveling in foreign lands for seven months? Old Jobst had had second thoughts about the boy. While Kepler was in Swabia, his gentlemen delegates had continued their negotiations and had finally been successful. They sent word on to Swabia. While in Tübingen, Kepler heard from Papius, his old friend who had been rector at the Lutheran
Stiftschule
in Graz when he arrived, that the family had agreed and that all was well. The bride was his.

He had been looking forward to this marriage for more than half a year, but then, on his arrival in Graz, he noticed that no one had stepped up to congratulate him on his upcoming marriage. He wondered about this and feared some disaster, when a friend pulled him aside and told him that it was true, the Müllers had canceled the marriage. In spite of Kepler's nobility and his newfound notoriety, he simply didn't make enough money to satisfy old Jobst. Kepler took sick with an irritated gall-bladder and depression. “Rage, audacity,” he wrote in his journal. “The position of the stars is powerful, calling out passion, hurt, and fever.”
⁹

In the seventeenth century, marriage was never an affair between the bride and groom alone, but a complex political dance between two families. And not just them—the whole community got involved. Public sentiment was so strongly in favor of Kepler, the jilted bridegroom, that whenever the Müllers showed their faces in public, they had to put up with sniggers and ridicule, satiric verses and unkind humor. Moreover, the church authorities paid a visit to the Müllers and, in good Lutheran fashion, instructed them on their duties. Eventually, old Jobst caved. The marriage was on once again. Poor Kepler, caught in the whirlwind of an off-and-on-again love, was turned round, first by joy, then by depression, then by joy once again. Just as he had come to accept the fact that he would not be married to Barbara, the marriage was back on. “That is how little control each man has over his future,” he wrote to Mästlin.

Then something happened that added a touch of vinegar to Kepler's
relationship with his old teacher. In March, just a month before Kepler's wedding, Mästlin sent a dyspeptic letter to Kepler, complaining about how much time and effort he had given to the publication of
Mysterium Cosmographicum,
so much so that he had neglected his own work, his fiery critique of the new calendar, that papist invention designed to subvert the spiritual independence of good Lutherans everywhere. Kepler didn't agree with his old teacher and told him so in a return letter, for Kepler was not only a mathematician and astronomer, but also a historian, and he knew the history of the Gregorian calendar better than his teacher. His view was practical to the core.

The European calendar used by Christians throughout the Middle Ages had first been commissioned by Julius Caesar, whose astronomers and soothsayers had informed him that the year was 365
¹
/
₄
days long. The problem was that Caesar's astronomers and soothsayers were wrong. The year is not 365
¹
/
₄
days long, but a few minutes shorter than that. The Council of Nicea (325) set down the rules for determining Easter based on the first day of spring, the equinox, but then later, in the middle of the Dark Ages, St. Gregory of Tours (544–595) wrote that these calculations were becoming a problem, because the equinox kept creeping backward, moving earlier one day every 128 years. In 750, the Venerable Bede reported that the equinox was now occurring three days earlier than the date set by the Council of Nicea. Eventually, said Bede, they would be celebrating Easter in January. Finally, the great medieval astronomer John Holywood, otherwise known as Sacrobosco, whose treatise, later called
The Sphere of Sacrobosco,
became the touchstone for all medieval astronomy, calculated that the observed year was 11 minutes and 14 seconds shorter than the Julian year.

Various solutions were put forth, but nothing actually happened until the sixteenth century, when Pope Gregory XIII handed the entire mess to Father Christoph Clavius, the famous Jesuit astronomer, commentator on
The Sphere of Sacrobosco,
and later adviser to Galileo Galilei. In papal circles Clavius was the local hero and certainly one of the great astronomical minds of the day. Clavius took an earlier solution proposed by Aloysius Lilius and simplified it, saying that the last year of each century
should be a leap year only if that year was divisible by 400, years such as 1600 and 2000. This still left standing a morsel of error in the calendar, but since this came to only one day in 3,333 years, Clavius thought it was good enough. The pope agreed, and published his bull
Inter Gravissimas,
which decreed that October 4, 1582, would then jump to October 15 to reset the calendar, which would henceforth, in perpetuity, follow Clavius's worthy scheme.

Mästlin hated the idea. He was not alone in this. All over Europe, people belittled this reform, and Mästlin headed the pack. Suddenly, Protestant and Catholic differences became all-important. Mästlin was not about to let the pope in Rome tell good Lutherans how to count time. He took to the intellectual streets, writing four diatribes against the calendar. Since the first one helped him get his professorship at Tübingen, his course was set. Intellectual fur flew all over Europe between Mästlin and various Jesuits defending Clavius, including Clavius himself. Attacking the calendar reform had become a bit of a cottage industry for Mästlin, and he was on his fifth diatribe when he turned aside for a time to work on Kepler's book. Too much time, according to Mästlin. After
Mysterium Cosmographicum
came out, he wrote that letter to Kepler, and Kepler, in typically undiplomatic fashion, wrote back:

This did not sit well. Mästlin did not respond immediately, but as years passed, his relationship with Kepler diminished, partly because of time and separation and partly because of old pique. Here was Kepler, his old student made good, now a famous man, and he had turned on Mästlin, his teacher. Over the years, Kepler tried to return to Swabia, to attain a position teaching at his old university, but was rebuffed each time. Bit by bit, Mästlin pulled away, until in the time of Kepler's greatest need, only a few years away, he turned silent. His letters never came. He sent nothing, no reply; there was only a dull, sullen silence.

Kepler saw none of this at first, because he was too often adept at not noticing. His wedding plans marched on, and for a time he was happy. In the midst of his happiness, however, dark clouds begin to form, a wisp here, a puff there. Old Jobst was not the only one to have had doubts. Kepler too fretted about the wedding. Though he loved Barbara, he was overwhelmed by the expense of the wedding celebration, much of which he had to pay himself. On April 9, only a few days before the wedding, he wrote again to Mästlin: “The state of my affairs is continually such that, if I should die within one year, no one could leave greater mayhem behind. I have to pay large expenses out of my own pocket, for it is the local custom to celebrate a wedding most glamorously.”

But money alone was not his greatest concern. What will happen to his hopes to return to Swabia and take up the ministry? “I shall surely be tied and chained to this place, whatever happens to our school, for my bride has property, friends and a rich father here.”
¹¹
Once he married Barbara, Graz would be his home. Although Barbara's money would never be his personally, part of his task in life would be to manage her money, lands, and estates along with his own. If Kepler was the irresistible force, Barbara was the immovable object. The Counter-Reformation was coming in force—everyone knew this. It was already there in the company of the Jesuits, in the person of the archduke. Kepler knew as well as anyone
that life in Graz could get warm indeed for a staunch Lutheran. If he married Barbara, with all her lands, his future could, indeed would, include a difficult choice between Barbara's desire to remain in her home and his own Lutheran faith. Kepler could not quit the land just to return to Swabia, to his own homeland, or to finish his studies for the ministry. If he married Barbara, he would be a family man, with responsibilities; he no longer had the freedom of his single youth.

Meanwhile, the forces of the Counter-Reformation were growing all across the Habsburg lands, including Austria, including little Graz. The Lutheran community, always at a disadvantage with the archduke, was beginning to watch the horizon for the coming storm. It would begin with an announcement, a tax on Protestant churches or a banishment of Lutheran preachers from the pulpit. Then it would escalate. The archduke could forcibly convert all Protestants in his territory if he wished, or he could exile them from the region. Either way, life for a good Lutheran would become increasingly difficult.