Kepler's Witch (15 page)

Kepler's own openness did not sit well with his fellow Lutherans any more than his stubborn Lutheranism sat well with the Catholics. The other teachers at the Lutheran school resented his exemption, wondering if he had compromised his faith along the way just to please the papists. He had certainly broken ranks with the other teachers by petitioning, but there was more to it than that. His beliefs, like his thoughts, were subtler than theirs. Some later scholars accused Kepler of indifference to dogma, but this too was unfair, for he did believe that there is but one truth, and he pursued that truth, which he identified with God, with all his heart all his life. Kepler had to go his own way, for the truth he pursued was inside his own conscience and did not float outside him among the dogmas of the churches. Sometimes he accepted the teachings of his church, and sometimes he did not, for he had to find the authentic truth for himself, and no one could find it for him. This meant that he could not accept the truth of others just because they told him to, no matter how authoritative they were. Neither armies nor pulpits could sway him by themselves, but only reason and faith.

Kepler's doubts about the ubiquity doctrine and about the sacrament had been paddling about in his head for years, since the days he had first studied at Maulbronn. Now they came to the surface. Perhaps unwisely, he confessed his doubts to the exiled church members, who were shocked and suddenly suspicious. Those who had envied his return and suspected him of compromise suddenly had new ammunition. The others merely shook their heads, wondering. None of them really understood him, though. His theological meanderings were well within the bounds of the
Lutheran faith. Or so he thought. But differences over what constitutes the heart of the faith are often the source of schism and of heresy. Kepler never quite understood this for himself, but others did, and from that day on they watched him carefully.

Once back in Graz, the hardest thing for Kepler to endure was the sudden loss of the church life that had kept him close to God. He felt the emptiness of the place—he missed the sermons; he missed the sacraments. There were preachers about still, tucked away in the castles of the various Protestant estates, but if any subject of the archduke were to ask for the sacraments, and if the preacher agreed, then that preacher could find himself on the road out of the archduke's territories, which included all of Styria, or Upper Austria. Surprisingly, though the Lutheran school had closed its doors, the school officials had kept Kepler on, partly because they felt sorry for him. They even paid his meager salary, but offered him no raise. Like Jobst Müller, the school councilors were practical men who enjoyed Kepler's growing fame, but did not understand his work and could see little value in it.

Kepler thought about leaving Graz, about finding another post somewhere else, at some university perhaps, maybe even at Tübingen, though he couldn't have known that the faculty there was set against him. But how could he leave? Barbara was attached to her inheritance, though Jobst balked at giving it to her. She had not yet seen a taler of her money from dear Papa. And the way things worked in Austria at that time, old Jobst, and not Barbara, was little Regina's guardian. Regina had inherited some 10,000 gulden from her own deceased father, and Jobst, as head of Barbara's household before she married Kepler, took control of it. After the wedding, Kepler received 70 gulden annually for Regina's upkeep, as well as the proceeds from a vineyard and the use of a house. Old Jobst had been trying to estrange the girl from Kepler in every way he could, though everyone could see that her stepfather was devoted to her. For Kepler's part, he would have missed his dear little stepdaughter if he had left town without her, because old Jobst, as her guardian, would have kept her with him. Most of all, however, he worried that she might fall under
the influence of the Catholics. Jobst had always been a Lutheran, but the depth of his faith was showing under pressure from the Counter-Reformation. When the time came, he scurried to Catholics, as did many of his relatives. No need to upset the archduke. Bad for trade.

So Kepler stayed on.

In the middle of all this, he naively found himself caught in a feud between two prodigious scientific egos. On one side was Tycho Brahe, the famous Danish nobleman turned astronomer. On the other was Nicholas Reimarus Ursus, “the Bear,” and Tycho's predecessor as imperial mathematician. Ursus had once been a swineherd, and his manners hadn't changed much since then. He was crude, abusive, and crafty, and his position at court was as much the result of theft as it was of accomplishment. When the
Mysterium Cosmographicum
came out, Kepler sent a copy to Ursus, asking his opinion. He wasn't above a little flattery, and heaped it on, calling Ursus the greatest mathematician of the age, and so on and so forth. Ursus never wrote back, but he kept the letter tucked away and dropped it into his next book, whole and entire. That was the book in which he stole Tycho Brahe's idea about the solar system and claimed it for his own, and then used Kepler to verify his brilliance. Tycho couldn't stomach Copernicus's idea of a moving earth, so he had cooked up a new system for himself, one that set all the other planets together orbiting around the sun, as Copernicus did, but then set the sun and the planets orbiting the earth, as Ptolemy did. Though it was more complex than it needed to be, it was a nice little bridge between the two systems.

When Tycho read Ursus's book, he was furious. Who was this Bear, this swineherd, to steal his work? And who was this Kepler to heap such praises on him? The first Kepler heard about it was in a letter from Mästlin. Kepler had sent two copies of
Mysterium Cosmographicum
along with a letter to Tycho at Wandsburg, and Tycho complained to Kepler by letter, protesting the theft and Kepler's part in it. That letter never arrived, but Tycho had sent a copy of his letter to Mästlin, and Mästlin sent a frantic letter off to Kepler, which did get through in late November 1598. Mästlin warned Kepler that he had made a fool of himself, that he had made a terrible mistake, and that his career was on the
line.
¹⁵
Mästlin said that Kepler should never have praised Ursus and reminded him that he had once told Kepler that the man's work was trash. Kepler didn't understand a thing, because he had never received Tycho's original letter, so he asked Mästlin to send a copy of the letter he had received from Tycho.

When the letter arrived, it wasn't as bad as Mästlin had made out.
¹⁶
Tycho had a few doubts about Kepler's polyhedral theory, but he found it ingenious and asked Kepler to try it on the Tychonic system, as he had done on the Copernican. Then he remarked that Copernicus's measurements of the planetary distances were not accurate enough to prove Kepler's theory, and that Kepler might find Tycho's measurements more serviceable. Then in a long postscript he complained to Kepler about his letter of praise to Ursus. He had no doubt that Kepler never realized that Ursus would include his letter in that “defamatory and criminal publication,” and he hoped that Kepler would supply Tycho with a short statement of the facts that would help Tycho in a court action he was planning against Ursus. The letter was velvet and iron, praise and complaint, and seemed to be an act of kindness. Still, Mästlin had informed Kepler that Tycho had written to him in a separate letter, complaining much more directly about Kepler's praise and criticizing the
Mysterium Cosmographicum
much more sharply.

Kepler was quite chagrined, for he did not want to burn any bridges with Tycho, a great man who looked kindly on his work, and so he wrote back at once, apologizing and defending himself, explaining that he had only meant to praise Ursus in a general way and had no idea that the Bear would publish his letter, implying that Kepler was a party to the scheme. “That nobody that I was then searched for a famous man who would praise my new discovery. I begged him for a gift and, behold, and it was he who extorted a gift from the beggar.”
¹⁷
Tycho was eventually mollified, but it took more than a few letters to do so. The incident jarred Kepler from his näiveté and forced him to enter the politics of the age.

As it turned out, Kepler certainly needed Tycho more than he needed Ursus to keep his own work going. What Tycho had said in his letter was correct. Tycho had the observations that he needed. While cooling his
heels in Graz, Kepler decided to push on with his astronomical studies and realized from Tycho's letters that Copernicus's astronomical data was not accurate enough. Kepler could see that his regular solids did not quite fit the data and that he would need Tycho's more accurate observations to verify the
Mysterium Cosmographicum
. But Tycho kept his observations to himself and would not pass them around, so Kepler would need to wheedle them out of him. Writing to Mästlin on February 26, 1599, Kepler said: “This is my opinion of Tycho Brahe: He has riches in abundance, which he does not quite use the way most talented people do. One has to take pains, therefore, which I did for my part, with all appropriate modesty, to wrest those riches from him, to beg him to disclose all of his observations, unchanged.”
¹⁸

The next few years would draw the two men closer together and into a collaboration that would change Kepler's life. After Tycho's death, Kepler would publish the data in Tycho's name and title them the
Rudolphine Tables
after Emperor Rudolf II. The one major disagreement between them, however, was over Copernicus. Tycho rejected Copernicus on theological grounds, while Kepler embraced him, also on theological grounds. Tycho believed that because humans were created in the image of God, then their little place in the universe had to be at the center. God placed them there so they could get a good view of the great cosmic show and thus come to praise and honor God even more. There was no greater theological master than the universe itself. Kepler agreed in principle, but Tycho's system still seemed overly complex and unwieldy to him, a patchwork compromise that was unmindful of the elegance of God's plan. God's plan must be rational, and rational meant geometrical, and geometrical meant elegantly simple. And so, while Tycho was thinking like an astronomer, Kepler was thinking like a mathematician.

However, there was still one worry, one tiny dark cloud, that bothered him. If Copernicus was right and the earth moved around the sun, then there should be some visible parallax, a shifting back and forth, of the stars from one season to the next, as an astronomer would first observe them from one side of the orbit and then from the other. However, no one could find any parallax. Tycho couldn't find it and used that fact as
evidence for the centrality of earth. But there were other possibilities. One was that the universe was infinite, as Nicholas of Cusa said, and then because the stars were infinitely distant, there wouldn't be any parallax visible. Still, Kepler couldn't accept that on general principle. The fact that the stars might not be at an infinite distance, but might be very, very far away was also possible, but Kepler had no way to prove that. Even Tycho's fine instruments couldn't have measured that. Such a discovery had to wait until 1838, when Friedrich Wilhelm Bessel observed the stars using instruments more refined than anything available in Kepler's day.

So Kepler went on to other problems. Why was the period of the moon's motion apparently longer in winter than in summer? Kepler explained that by mechanical forces, his
vis motoria
of the sun, coupled with another
vis motoria
of the earth itself. He also asked why there was a reddish color to the moon during lunar eclipses. This led him to raise questions of optics, which became important to him later. Finally, he burrowed into the question of chronology, trying to pinpoint biblical events through astronomical means. Herwart von Hohenburg involved him in trying to find the year of the Roman civil war between Caesar and Pompey, which Kepler placed at 51
B.C.

That summer of 1599, in the midst of all his astronomical work, was when his little daughter Susanna suddenly died and Kepler nearly fell into despair. Oddly enough, in the midst of his sadness, perhaps because of his sadness, he began researching a new book, a book that would eventually lead to his great work on world harmony, the
Harmonice Mundi.
This was perhaps more revealing of his personality than anything else. His world was collapsing about him. He was about to be chased out of his home and lose his career. His little son had died and now his daughter, of the same illness. His wife's family gnawed at him over everything, and there he was in his study thinking about a book on the harmony of the universe.

His faith told him that God does nothing without a plan and that God's wisdom and goodness made the whole world beautiful. Buried in the heart of the world is the image of the Creator, a copy of the divine
mind. God gave human beings the power to reason, the most godlike characteristic of all, and out of that rational power would come the ability to see God's own plan in action. Copernicus had seen it, that marvelous harmony, that order to things, like the order of music that heals the soul and harrows sin from the world. The sensation of joy that different tones played in orderly succession or played together in chords brings to the human soul speaks of a perfect world, higher than this earth where, like little Susanna, things are born doomed to die. But harmony speaks to the soul of the transcendent world where God sits enthroned above the stars and listens to the music they make. The pleasure people feel in music partakes in this and encompasses each whole person in the place where the intellect joins with the senses, just as mathematics joins with sound. Major thirds, minor thirds, major fourths, major fifths, each with its own unique feel. So what is it about these proportions that stirs the human soul so? Where does the joy come from?

Kepler, following Plato, believed that music, and the simple mathematical relations that music embodies, reveals a cosmic harmony. This was not a rough Pythagorean number mysticism, by any means, but an icon of the mind of God embedded in the human soul. “God wanted to make us recognize him, when He created us after His image, so that we should share in His own thoughts. For what is implanted in the mind of man other than numbers and magnitudes?”
¹⁹
As he later wrote in his defense of Galileo, his
Dissertatio cum Nuncio Sidereo:
“Geometry is one and eternal,” a reflection out of the mind of God. That humankind shares in it is one of the reasons to call the human being an image of God.
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