Kepler's Witch Read online

  As royals do, the couple often moved between castles, sometimes to his, sometimes to hers. One day, when they were living in her castle, which they had been doing for some time, the two of them wanted to see the wide lands unrolling all around them, so they climbed the battlements up into the highest tower, to the tallest spire, where there was a room made of stone with windows all around and firing slits in the walls for archers. Behind them, the whole court huddled on the steps, breathing hard from the climb, gossiping here and there and speculating about whatever business the prince and princess had up in the tower. Outside, the evening gathered, rose-colored, with green and brown fields all around, bluing slowly in the distance, out to the edge of the forest, and then deepening to purple near the horizon. Swallows wheeled and hummed, snatching mosquitoes from the air. It was an evening ready for prophecy.

  Suddenly, the world hushed. Princess Libuše stretched out her hand to the evening and pointed into the distance. A light gathered around her. The court quieted, fearing to breathe and break the spell—even the birds fell silent.

  “I see a great castle and its glory reaches to the stars,” the princess said. “The place lies deep in the forest—the Brusnice river valley guards it from the north, while a rocky hill protects it from the south. The Vltava winds between, at the bottom of the great hill. Go there,” she said, “and on the left bank of the river, you will find a man carving the doorway of a new house. You will build your castle there and name it ‘Threshold,’ Praha, the sacred doorway leading into hearth and home, to warm fires and to meat on the spit, and finally leading into the place of the dead. You know that tall men must bend their heads to enter any doorway. So will all, tall and short, men and women, bend before this castle, and one day it shall be a great, golden city.”

  The prince and the men of the court tried to follow where Libuše pointed, but could see nothing but the night. Then, after a time, the princess fell back, the light of prophecy fading from her. The birds sang once again, and the court buzzed with gossip. The next day, the men packed their horses and set out to find the place. Quite soon they found the valley, just as the princess had described it—the narrow river valley to the north, the great hill to the south, the winding Vltava in between. And there, near the river, they came upon a man carving the lintels of a doorway. The men of the court set to work building the castle. They felled trees and opened up new lands; they built a rampart and a great hall, just like the one at Vyšehrad, at the court of Prince Pøemysl. This new castle was bigger, however, greater and taller than any other, built as Libuše had said, on the left bank of the Vltava. Its fame grew and has lasted even to today.1

  IT IS LIKELY THAT KEPLER, on his way to Prague via Linz, never realized his good fortune, never realized that his life was about to change for the better. It is likely that all he could see was a future full of darkness. Tübingen had abandoned him, though. Hoping against all evidence to the contrary, he still waited for word, waited for some letter from his old school that would change his life. Other prospects and other universities were vague chances at best. And attaching himself to Tycho was risky. Kepler, his wife, Barbara, and his daughter, Regina, with all their worldly possessions stuffed into two little wagons, rode behind a plodding horse on their way to Linz. Kepler, his face drawn with fear for the future, wondered how they would all survive. The trip to Prague was no great adventure, no wonderful new thing—it was an act of desperation. Kepler was a refugee—the greatest tragedy that could befall a man, finding himself on the highway, banished from his home, with no way to support his family and with nothing but poverty following behind. He was fearfully, agonizingly homeless.

  When he and his family arrived at Linz, Kepler asked about the letter he had hoped would be waiting for him there. He was praying, irrationally perhaps, for some magic word from Mästlin, a change of heart from the faculty that would, in spite of everything, call him back to Swabia, where so much of what he knew and loved resided. But no such letter had come, and Kepler’s last hope of returning home died. What should he do? What could he do? He decided that he could not leave his family behind in Linz among strangers, for fear that one of them might sicken and die, far away from her friends and family. So he left his household goods in the care of someone in Linz and, taking Barbara and Regina with him, he set off for Prague.

  On the road between Linz and Prague, he took sick. The distress, the exhaustion, the desperation encircled him, and he fell into an intermittent fever, a febris quartana that would level him for the rest of the year. The fever swelled for about four days, sucking the life out of him, and then it would fade only to return a few days later. Was this malaria? Or typhus? While on the road, weakened and shivering, he sent a letter to Tycho Brahe announcing his arrival.

  Tycho had hoped to establish a new Uraniborg at Benatky and had sent his son with Longomontanus to fetch the four great instruments he had abandoned on Hveen when he left the country. Because of bad rains and swollen rivers, because of one bureaucratic tangle after another, the instruments did not arrive in time. A recent outburst of plague had sent the imperial court scuttling from Prague, but then after the plague subsided, the emperor returned. Fretting over the future, Rudolf suddenly needed the astrological advice of his imperial mathematician and on June 10, 1600, sent for Tycho. Tycho took residence near the palace, because the emperor often commanded his attendance twice a day.2 He set up his household at an inn, the Sign of the Golden Griffin, built on the slopes of the Prague Castle, the emperor’s palace.

  The letter from Kepler was businesslike, full of hidden bravado.

  Though I was not able until now to write to you about my business with you, I am writing now partly because of my desire to communicate to you my reasons for travel to Bohemia, which I have been best able to do while on the road. Your letter containing my appointment only reached me after I had left the Steiermark and had come to Bohemia. I have several points. The first arises from the contract that we signed last May and have already closed. In it, I promised, with the consent of the emperor, to work at your disposal on some area of astronomy for two years, in which time you would help and support me. The second point refers to my present state of distress, because it is the will of the local authorities that I emigrate, and I request that you give insurance, either by recommending me to the emperor or by helping in my state of emergency to relocate to Prague.

  Bereft of everything, Kepler’s pride was touchy. He certainly did not want to appear like a supplicant before Tycho; and he would not allow himself to become one more in Tycho’s battalion of servants or one more mouthpiece for Tycho’s theories. He had a reputation of his own to defend, a theory to prove, and, after all, he did not completely agree with Tycho. Perhaps he had overstated his case in his letter, pretending that he had more prospects than he had. Perhaps he had hidden Tübingen’s rejection, for he didn’t want to admit that his own people had abandoned him. It was true that Tycho had invited him even without his salary from Graz, but he was a destitute man, and he did not want to look destitute. In the letter, he told Tycho that as a scholarship student, he needed to travel to Württemberg to ask the duke for his support and for the support of the duke’s ambassador at the imperial court. He was looking into a position at a university, perhaps Wittenberg or Jena or Leipzig. He made it sound as if the professors at Tübingen had also offered him a position and that he was trying to make a choice between several lucrative opportunities. However, he said, if Tycho had a position for him, then he would certainly give him first choice.

  Kepler arrived in Prague on October 19, 1600. He was in a bad way—depressed, nearly broke, shaking with fever, with his wife and stepdaughter on the verge of illness themselves. He sought refuge in the house of Baron Hoffmann, where he was warmly received. The fever carried on, however. He began to cough and feared tuberculosis. Added to that were money problems. The cost of living in Prague was so much higher than in Graz that what little money he had was rapidly disappearing. In Graz, he had made only 2
00 gulden a year, and it had cost him 120 to move his family to Prague. Barbara complained constantly. Because of her husband’s religious scruples, she had been torn from everything she ever knew and loved. Her father’s conversion, on the one hand, and her husband’s refusal to convert, on the other, must have torn the poor thing apart. Besides, as the daughter of a rich man, she was used to a much higher standard of living. Everything was so much more expensive in Prague that Barbara had to live like the poor. She soon fell into a terrible depression, missing her family, missing her city and all that was familiar to her, and then she too fell sick.

  Tycho, meanwhile, received Kepler warmly. Tycho was a builder and an observer, a gatherer of information, and although he was a master of astronomy and calculation, he lacked Kepler’s sublime fire, his lightning insight into how things fit. If he wanted a true victory, he needed someone who could take his observations and fashion a proof out of them. The bare observations alone wouldn’t be enough. They had to be sorted, calculated, and woven into the right patterns to prove the Tychonic system, and that required Kepler. Besides, it was hard to hold on to good assistants. He had gathered good astronomical minds from all over Europe, but after a time, one by one, they found other positions, returned home, or set out on their own. Tycho wasn’t all that easy a master. Therefore, he worked hard to secure a position for Kepler, not only with his own staff, which he was willing to do in spite of their often prickly relationships, but also with the imperial court. The emperor, for his part, was well disposed toward Tycho, partly because he needed him for his astrological advice and partly because he was an expert in all the little machines the emperor loved so well. He was therefore well disposed to any suggestion that Tycho might have had for Kepler.

  But the emperor was not completely his own man. He was surrounded by an imperial bureaucracy that seemed to go on in Byzantine fashion for miles and miles. To secure a position for Kepler would not only require the emperor’s approval, but the approval of every little bureaucratic head in every little bureaucratic office down every little bureaucratic corridor in the palace. One of their functions was to make sure that things did not happen, because when things happened, it cost money. They excelled at this job. As with all governments, without a strong hand from the emperor, the imperial bureaucracy was glacial, so that no matter what Rudolf wanted for Kepler’s salary, the money somehow never showed up, and Kepler quickly became dependent upon Tycho.

  In December, the last nail in the Tübingen coffin was hammered in; the last of his hopes for that university was crushed. The letter he had looked for arrived, but his former teacher offered him no advice, no comfort except for his prayers. Kepler wrote back at once: “I cannot describe what paroxysm of melancholy your letter has occasioned me, because it destroys all hope of going to your university. So I must stay put until I either get well or die.”3 Several weeks later, he wrote once again, this time begging:

  I long for consolation, for I am still suffering from the Wechselfieber, the intermittent fever, and from a dangerous cough. I suspect consumption, which may take my life. My wife is also ill. Not four months have passed and I have spent one hundred taler in Prague. On top of that, little is left of the travel money. Tycho keeps promising me that if everything were up to him, no one would be happier than I. My impatience and the significance of Easter time are prophesying my impending death, and if so, I shall depart this world around the Easter holiday. The love of my homeland is tearing me away, whatever its future destiny shall hold. Once before, however, I was there when my world fell apart, so now I have a fearless spirit.

  Tycho is very stingy with his observations, but I am allowed to copy them daily. If only the transcript were enough. Therefore, a selection is necessary. The illness leaves me gloomy. I have been burdened too much with the gift of darkness. I am unsatisfied with myself.

  Longomontanus, homesick for Denmark, had already left Prague by the time Kepler had arrived, and so Kepler was able to take on the problem of the orbit of Mars once again. He worked on it diligently, as much as his health would allow, which would have been enough by itself, but Tycho assigned Kepler one more task, one that troubled him deeply. Returning to his old battle with Ursus, he set Kepler to work on a refutation of the dead man’s ideas. Perhaps Tycho wanted Kepler to prove his loyalty, but more likely Tycho was just old-fashioned and an enemy was an enemy. Like Ahab after the white whale, he would not let go of Ursus and would chase the man into his grave and argue with his ghost. Kepler did as Tycho asked, though he found it a waste of time and believed that it was unseemly that men who studied the secrets of God would behave in this manner. As he wrote Tycho’s defense, therefore, he did it with a remarkable sense of balance. He kept all personal rancor out of the text and, instead, refuted Ursus’s hypotheses one at a time. In doing so, he defined what an astronomical hypothesis was, rejecting the idea that it was simply a matter of correct conclusions arrived at by calculation.

  Then Kepler received word that old Jobst Müller had died, and in the spring of 1601 he traveled south to Graz once more to settle his wife’s affairs. Surprisingly, in spite of all the threats that the archduke had fired at the Lutherans, Kepler wasn’t arrested. No one in the Counter-Reformation seemed to care or even notice that he had returned. If he had stayed longer, perhaps they might have. The archduke’s government in Graz looked the other way, and the Lutheran community, or what was left of it, warmly received him. The trip apparently did him a world of good. The fever abated, and he was able to travel in and around the city in some comfort. He had the energy to climb Mt. Schöckel, where he made measurements of the curvature of the earth and witnessed a strange thunderstorm.

  In the midst of his joy, however, troubles exploded with Tycho once again. Tycho had promised Kepler that he would provide money to take care of Barbara and Regina while he was away, but then suddenly, while he was still in Graz, Barbara wrote Kepler a letter complaining that she was receiving too little money and that household goods were costing too much. She complained further that Tycho was too stingy and that life in Prague, for all its golden beauty, was not as gracious or as comfortable as it had been in Graz. Fired up, Kepler wrote to Tycho and passed on his wife’s complaints is if they were his own.

  Tycho angrily responded through his pupil Johannes Erickson that Kepler should consider what Tycho had already given to him and to his wife and that the Keplers should have more respect and be more moderate with their benefactor, who was helping them in every way possible. This angered Kepler in turn because he did not want to be a charity case; he wanted to be paid for his work, work central to everything Tycho was doing, and given the respect that one colleague would give to another. But as late middle age began to settle on Tycho, he was less and less willing to compromise. He had grown irascible, even with the powerful members of the emperor’s court. He worried over his rejection by the Danish king and all the other events that had brought him to the emperor’s court. For all his wealth and noble birth, Tycho had also come to Prague as a refugee. He was a man out of place in the city, and though he was well traveled, as he grew older he yearned increasingly for his homeland. As Kepler said, “He was not the man who could live with anyone without very severe conflicts, let alone with men in high position, the proud advisers of kings and princes.”4 Gradually, the loss of his homeland, the stress of his position as imperial mathematician, and the pull and tug of imperial court life began to show on the old man, and he acted more like a petulant child.

  At bottom, Tycho was a good sort with a good heart; he tried to do the right thing, but he was also feisty, and his own pride subverted him. In that, he was a lot like Kepler. Tycho protected his observations like a wolf guarding her cubs, and he showed Kepler only those observations that were germane to the work he expected Kepler to do. Such miserliness was a symptom of the age. Kepler was more open-minded than most, and in some ways more modern. It infuriated him that other astronomers, including his teacher Michael Mästlin, refused to work with each other,
guarded their own observations like dragons, and hoarded their data as if it were spun of gold. Throughout his career, Kepler encouraged other astronomers to share their work, to advance general knowledge, but got little response. Each astronomer was too worried about his reputation, his place in court, the opinions of his patrons, as if one man could own all knowledge. Tycho was typical of the times, more interested in advancing his own fame than the discipline. On Hveen, his island fiefdom in Denmark, he had set up a printing press to publish his works and observations. No other printer could touch the data, for Tycho demanded absolute control over his work.

  After a few months, Kepler returned to Prague from Graz feeling well. The spat with Tycho had blown over, the fever that had plagued him had passed, and he had benefited from the kindness and hospitality of his old friends in Austria. Almost immediately, Tycho introduced him to the emperor, who received Kepler graciously and commissioned him to collaborate with Tycho in compiling new astronomical tables based on Tycho’s observations. Tycho begged the emperor to allow him to name the tables after the emperor himself, which Rudolf agreed to, and so the new book would be titled the Rudolphine Tables. Kepler was included in the project as a collaborator, not an assistant or servant. Kepler’s life had suddenly changed; his future was secure. Tycho also did something he had done with few others. Knowing that only Kepler could prove his Tychonic theory, Tycho entrusted him with his precious data, the keys to his heavenly kingdom. Kepler suddenly had everything he needed.

  Then, however, his life changed once again. Kepler had been sick for nearly a year, and only through his trip to Graz had he been able to cleanse his body and soul. Now, suddenly, it was Tycho’s turn. Things were going well between him and Kepler, and there was finally some peace in the house. Kepler had received the recognition he desired, and in the emperor’s own words he was no longer a subordinate, but a collaborator. Then, suddenly, Tycho took ill, with an illness that would lead to his death. A few days after Tycho had presented his new collaborator to Emperor Rudolf, he went with a friend, Councilor Minckwicz from the imperial court, to a luxurious banquet given by the old patron of Edward Kelley, Peter Vok Ursinus Rozmberk, at his house near the gate to the Prague Castle. The rules of civilized behavior at the imperial court were decidedly medieval and required that all guests remain seated at the table until the host finished his meal and signaled the end of the banquet by rising and leaving the room. According to an account of the event that appeared at the end of Tycho’s personal papers and observations, an account that scholars later decided was penned by Kepler: “Holding his urine longer than was his habit, Brahe remained seated. Although he drank a little overgenerously and experienced pressure on his bladder, he felt less concern for the state of his health than for etiquette. By the time he returned home, he could not urinate anymore.”