Tycho and Kepler

by Kitty Ferguson

  On the other hand, Kepler’s faith and his knowledge and experience of the way God guided the lives of men and women, as well as his sense of duty, told him that he must not be selfish. He hadn’t been put into the world for himself alone. If it was God’s will that he go to Graz and teach mathematics, he should not insist that he had a “higher calling.” Furthermore, he had promised himself, when he had seen friends employing every device possible to avoid obedience when faced with similar distant postings, that he would be more dignified if it happened to him. Recalling that noble resolve, he admitted ruefully that he had thought he was “tougher than I actually10 was.”

  Kepler consulted his two grandfathers and his mother. Though disappointed that they would not see him in the pulpit, all thought it best to follow the advice of the Tübingen faculty. Kepler managed to engineer a compromise that left open the possibility of returning to service in the church, and with that settled he agreed to move to Graz.

  The transfer was set in motion. Kepler could not go without the permission of the duke of Württemberg. Officials at Tübingen and the inspectors of the school in Graz sent letters requesting that Kepler be allowed to leave the duchy, and the duke gave his approval.

  The twenty-two-year-old Kepler left his beloved Tübingen on March 13, 1594, with a heavy heart. The move to Graz was a venture into alien territory. Even the calendar was different: Because Württemberg still used the old Julian calendar, Kepler lost ten days when he came to the border of Bavaria, where they used the newer Gregorian calendar. He arrived in Graz, by that calendar, on April 11. Kepler trusted the will of God, but he could not have imagined how essential this strange, unexpected, seemingly senseless journey was in getting him to his future, to Tycho Brahe.

  WHILE KEPLER WAS BASKING in the rarefied scholarly atmosphere of the University of Tübingen, at the close of the 1580s and during the first years of the 1590s, the utopia of Uraniborg had begun to fray a little around the edges.

  The Tycho who had built Uraniborg and Stjerneborg had usually enjoyed good relationships with most people. He did have serious conflicts with the peasants on Hven, but the customs of the time and the islanders’ unusual immunity from those customs prior to his arrival made those conflicts almost inevitable. Otherwise, Tycho seems to have commanded genuine respect. He had founded and presided ably over an entirely unprecedented institution that drew both humble students and a scholarly elite from all over Europe and Scandinavia. Even in those days when an aristocrat could expect obedience, he had to have been a skilled manager. Students and assistants worked for him untiringly and apparently with great devotion. His ability to recognize the potential of men of lower classes and his willingness to elevate them to the level of valued colleagues—Steenwinkel being a case in point—set him apart from most of his aristocratic peers. He seems to have been a faithful husband to his commoner wife, concerned about his children, popular among commoner scholars and friends such as Pratensis, and well liked by royalty such as King Frederick and Wilhelm of Kassel. To a remarkable extent for a nobleman living at the end of the sixteenth century, Tycho had chosen to ignore the chasms between the social strata and had managed to bridge them.

  His relationship with a new assistant who came to Hven in 1589 exemplified his continuing success in doing so. Longomontanus, as the man called himself, was the Latinized name for the farm where he was born in western Jutland to a poor peasant family. Poverty and the need to help his widowed mother run the farm had delayed Longomontanus’s education, but the pastor of the local church had recognized his potential and seen to his schooling. Longomontanus was twenty-six by the time he entered the University of Copenhagen. Scarcely a year later, in 1589, he came to Uraniborg on the recommendation of his professors and was soon one of the most skilled and exacting astronomers there. His humble origins did not prevent his becoming one of Tycho’s favorites and an intimate friend of the family. Tycho trusted him sufficiently to make him his personal secretary. Longomontanus was popular with Tycho’s two sons, Tycho and Georg, and Tycho chose him (perhaps because of his maturity) to chaperon them when they traveled to visit relatives.

  Nevertheless, in spite of his lack of regard for social divisions and the scorn he had poured on the nobility, Tycho had not ceased to be an aristocrat. It was in his blood and upbringing. If for him the traditional nobility had stopped being much more than a weary charade, the symbolism of Stjerneborg indicated that it had been supplanted by a much more vigorous and much older aristocracy, in which Tycho saw himself the heir by divine right to Hipparchus, Ptolemy, and Copernicus, men who left kings like Frederick in the dust. Nor had Tycho shed the trappings and pride of nobility. He had transformed them, with embellishments, to adorn this different kingdom. Here, the old social class distinctions really had, to a certain extent, become extinct, but Tycho was still on the top—higher, in fact, than he had been in the old order, and potentially more of a tyrant.

  The picture of Tycho that has chiefly come down in history is not a sympathetic one, and a few years later he would appear mercurial, autocratic, and paranoid to Kepler, who was initially inclined to revere him. The finer side of Tycho never disappeared completely, and previous instances of tyranny and paranoia may have escaped the records, but evidence points to a change in his temperament in the early 1590s. In the autumn of 1590 he imprisoned his tailor for three days before the man succeeded in escaping from Hven by night. In 1591 Tycho’s jester, a dwarf named Jepp, tried to flee from Uraniborg, and Tycho had him beaten. None of that was perhaps out of character for the lord of a fief, but as the decade continued, there was increasing evidence of a less likable aspect to Tycho’s personality.

  In the spring of 1591 Tycho’s concentration on astronomy suffered serious disruption from an embroilment with a gentleman tenant, Rasmus Pedersen,11 who lived on a small manor in Zealand that was part of Tycho’s holdings as a canon of Roskilde Cathedral. The incident began when Pedersen purchased from Tycho a life tenancy of Gundsøgaard, an unprofitable estate with only nine cottages and the ruins of a manor house that had recently burned down. Tycho cannot have charged him very much for this holding, and he was chagrined when Pedersen unexpectedly turned it into a thriving establishment and rebuilt the house into something large and quite splendid. Pedersen may or may not, in the process, have overstepped his fishing rights and exploited his nine peasant families beyond the usual norm. There were reports that after using their free labor for his building project, he forcibly ejected them from their small plots so that the land could become fields of the manor, then used their free labor again to build new cottages, and finally obliged them to buy the cottages from him.

  Motivated either by concern for the peasants or a desire for the manor house, or both, Tycho attempted to renegotiate the lease and, when Pedersen refused, seized the manor and expelled him without a refund. But Pedersen was persistent: When Tycho ordered the fields at Gundsøgaard to be plowed and sown, Pedersen had his retainers sow fifty-two and a half bushels of rye right behind Tycho’s sowers. Tycho escalated the conflict. His men seized Pedersen as he was dining and brought him in irons to Hven, while others of Tycho’s agents confiscated Pedersen’s business records and detailed reports about the estate. Tycho imprisoned Pedersen at Uraniborg for six weeks until Pedersen agreed to sign a capitulation. By the spring of 1591, Tycho had brought the matter to court.

  A few months later, Tycho’s appeal to the king and the Rigsraad failed when even Tycho’s aristocratic peers, who might have been expected to side with one of their own, were unwilling to view his treatment of Pedersen as normal behavior for a feudal lord. On the way home to Hven, the disgruntled Tycho voiced his disappointment by composing a Latin epigram complaining of this unfair decision. He did not drop the matter. His next maneuver was to try to link Pedersen with a drowning in a well. That failed. By November 1592 Tycho was holding Pedersen’s brother and a servant as prisoners. There is no record of the result of a second hearing, for which Tycho was allowed to nominate some panelis
ts to participate in the decision, but two years later he seems to have regained possession of the manor house of Gundsøgaard. There are no further records concerning Pedersen.

  Possibly while Tycho was holding Rasmus Pedersen prisoner at Hven, a young man named Georg Ludwig Frobenius arrived. As Frobenius described events in his memoirs,fn1 12 he had received his master’s degree from the University of Wittenberg, worked for a year as a tutor in Saxony, and gone to Denmark, afire to visit Uraniborg and meet Tycho Brahe. He made the initial mistake of seeking entrance after everyone had gone to bed. He might have been forgiven for thinking that since this was an astronomical observatory and it was “a beautiful, clear, and calm night,” the entire household would not be asleep. However, despite the glowing letters of introduction that Frobenius presented, the porter at the gate turned him away. With the savage barking of the mastiffs kenneled above the gatehouse ringing in his ears, Frobenius walked off to spend the night hungry in a field.

  Early the next morning Frobenius tried again at the gate, and Tycho granted him an audience. After conversing with Frobenius and reading his letters of recommendation—one of them from Tycho’s friend Caspar Peucer—Tycho agreed to accept Frobenius as a student. He would have free bed and board and an assigned seat at the dinner table.

  Though several languages were spoken at Uraniborg, Danish was the most common, and Frobenius knew no Danish. From the start he felt excluded, particularly at meals, where he was seated beside a student from Bergen, Norway. However, things must have gone rather well, for about a month after his arrival Tycho asked him, through other students, whether he would like to remain at Uraniborg “to serve him in the study of astronomy.” Frobenius replied enthusiastically. He would be pleased to stay for one, two, or three years, if the terms of employment were acceptable. Since most contracts for service at Uraniborg were for three years or less, Frobenius had not asked for special favors.

  Nevertheless, at this point there was a mysterious alteration in Tycho’s attitude toward Frobenius. The conditions of the contract, as Tycho laid them down, seemed intentionally framed to make it impossible for Frobenius to accept. Frobenius was shocked and somewhat affronted to hear that one, two, or three years were out of the question. He would have to commit himself for six years minimum, pledge never to reveal anything about Tycho’s inventions to anyone either now or after he left, take no notes for his own benefit or later personal use, and “serve without hesitation wherever [he] could fruitfully be used, in any of [Tycho’s] astronomical or pyronomical labors.” He would eat at Tycho’s table, but there would be no salary or clothing provided by Tycho, who preferred “to grant to me whatever happened to come my way.”

  Frobenius took a deep breath and asked for time to consider. Then he replied that he could not agree to such a long period as six years. He wanted to visit foreign lands and learn foreign languages—as Tycho himself had done—and eventually probably pursue a career in medicine or law. Though he was willing to promise not to reveal or spread abroad any information about Tycho’s inventions or observations, he was reluctant to promise never to utilize knowledge gained at Uraniborg to benefit his own studies, for it would be a waste of time to learn things he could never use in the future. Also, he needed a fixed salary, not just bed and board.

  Contract negotiations with prospective assistants were not unusual, and Tycho was often willing to bend on the length of service and adjust other clauses. Not so in the case of Frobenius. Meanwhile Frobenius learned that his situation was disturbingly paradoxical, for though Tycho’s terms of employment seemed designed to force him to leave, other students and assistants told him that it was extremely difficult to get away from Uraniborg. Hans Crol, who was, like Frobenius, German, said it would be impossible to escape the island unless he could find a good pretext.

  The distraught Frobenius recalled that he had in his possession letters of reference to other people besides Tycho, one of which might provide him with an excuse to take a leave of absence from which he would simply not return. The letter that looked most promising was to Heinrich Rantzau in Holstein. Frobenius requested leave for only a few weeks to go to Holstein, claiming to have been entrusted with an oral message to Rantzau that could not be delivered by anyone else. At first Tycho, perhaps suspecting Frobenius’s intentions, refused his permission. Frobenius then offered to leave all his belongings in his trunk at Uraniborg as security for his return. Tycho finally acquiesced, with the strange requirement that Frobenius seal the trunk on all sides. Tycho and Frobenius traveled together to Copenhagen. When they parted so that Tycho could attend a meeting of the Rigsraad, Frobenius found a ship bound for Lübeck, hurried aboard, and sailed away with only “a couple of shirts, a cloak, and handkerchiefs in a black linen satchel.”

  It is tempting to wonder whether some of Tycho’s assistants were playing a practical joke on poor Frobenius, whether he made the story up, or whether he was perhaps a difficult and vindictive person himself. Tycho in fact allowed many students and assistants to leave Uraniborg for posts elsewhere. Most continued to be his good friends, and he viewed it as an advantage to have a network of them all over Europe. Crol, who warned Frobenius about the difficulty of escaping, was at the time an embittered man because of the recent death of his son. Crol himself never left Uraniborg and died in the autumn of that same year. Tycho grieved for him and praised his memory as a fine goldsmith, instrument maker, and observer.

  Conflicting opinions and reports are, of course, not unusual about men and women whose lives for one reason or another tower over the people around them. On the one hand there are those who revere them and either do not experience or choose to forgive treatment that others regard as insulting or abusive. On the other hand there are those who, wearing different spectacles or having somehow inadvertently fallen foul, experience that greatness as having a nasty side indeed.

  fn1 Frobenius’s story remained unknown until John Robert Christianson discovered his memoirs in the late 1980s.

  11

  YEARS OF DISCONTENT

  1588–1596

  IN THAT SAME spring of 1591, when Pedersen was in Tycho’s dungeon and Frobenius was upstairs plotting his escape from Uraniborg, Tycho received a letter from Wilhelm, the landgrave in Kassel, asking about an animal that Wilhelm called a Rix.1 Wilhelm had heard that a Rix was taller than a deer and native to Norway, and he inquired whether Tycho might have a picture painted of a Rix and sent to him. Tycho suspected that the landgrave meant a reindeer and was hinting that Tycho might send not merely a picture but the animal itself. Tycho did not have a reindeer, but he had an elk, so he offered to send that. No, the landgrave replied, he already had an elk, and it was not a reindeer he wanted either. He had had one of those before, and it had not survived in the climate of Kassel. A Rix was what he wanted. Nevertheless, he would not turn down an elk or two if offered.

  Tycho had an elk brought from Norway to Copenhagen, where it was to wait at his niece’s home until it could be shipped. Unfortunately, the elk mounted the steps of the manor house, got into the beer supply, and consumed so much beer that it fractured a leg trying to get back down the stairs and died.

  In the course of correspondence with Wilhelm around this pitiful story, the first hint came from Tycho himself that he was not entirely happy. He went so far as to tell Wilhelm in rather cryptic language that he might choose to venture into other climes, the sky above being available for study anywhere. He did not specify what was troubling him. Perhaps it was only a temporary low mood or annoyances like Pedersen and Frobenius that he had largely brought on himself. But there is reason to suspect that one cause of Tycho’s discontent, and his poor handling of those annoyances, was something more significant—a crushing disappointment in his astronomy.

  Tycho did not, in this correspondence with Wilhelm, learn of Bär’s visit to Kassel, but Bär had never been far from Tycho’s mind. Tycho’s book about the comet, with the chapter about the Tychonic system, had come out in April 1588. He mentioned nothi
ng about the success of the 1587 parallax observations in the book, but not long after its publication he wrote to his friends2 Caspar Peucer and Christoph Rothmann, saying that he had observed the parallax all the way back in 1582. That claim flatly contradicted an earlier letter that he had written in 1584 to a professor with whom he had studied at Rostock, Heinrich Brucaeus. Tycho had reported to Brucaeus that in the observations made in 1582, he had been unable to find a parallax for Mars, and that the Copernican hypothesis had therefore to be rejected. In 1587 he had seemed a little less certain of that negative result when he had written Wilhelm, in Kassel, that (based on those same 1582 observations) he was more confident he would find a parallax. Then, in 1588, he told Peucer and Rothmann (still referring to the same 1582 observations) that he had finally succeeded. In November 1589 he repeated that claim in a letter to Thaddeus Hagecius, stating once again that all the way back in 1582 (two years before his 1584 letter to Brucaeus saying the opposite) he had observed a diurnal parallax and that it had been large enough to convince him that Mars comes closer to Earth than the Sun does. In the same letter to Hagecius, Tycho also spoke of the Tychonic system that he had “thought out . . . very nearly six years ago.”

  The puzzle was, and is, why the 1582 observations were so important to Tycho that he kept harking back to them, making contradictory claims about their results. He had designed and built several instruments after 1582 that were much more capable of making this measurement. Kepler later examined Tycho’s observations of 15823 and reported that he could find no evidence in them for a Mars parallax. Subsequent knowledge of the solar system has confirmed that there could have been no evidence of one there. Yet in 1588 and 1589 Tycho’s letters insisted there was.