Kepler's Witch

by James A. Connor

  Mydlár and his assistants dressed themselves in black robes and masks. A large crucifix stood in front of the chopping block so that each of the victims could see the face of Christ just before his head was chopped off. A group of magistrates also dressed in black sat on the balcony of the town hall. Three of the magistrates took on the task of calling for the victims, one by one, then rushing back inside, black robes flapping like crows, to haul out the next one. Trumpets cried, drums rolled as if in some magic show, and a magistrate disappeared into the town hall. He led the next man forward to the place where Mydlár leaned on a bare sword, honed and cared for like a chef’s knife. The executioner stood calmly, waiting for the next death.

  The magistrates offered each man a chance to speak, to pray, to explain his life, to beg for mercy. The condemned men said good-bye to the world, their friends, and families; to show their superior Christianity, they begged forgiveness for any suffering they may have caused, prayed to God, forgave their killers, and at the instructions of the executioner knelt in place and stretched their necks upon the chopping block, slimy with blood. Each man looked upon the soft face and form of the suffering Jesus as the sword fell and ended his life. Then six holomci, special servants of the executioner who carried the dead, all dressed in black masks and cloaks, like riders from the Apocalypse, picked up the headless bodies one by one, the arms and legs still twitching, and carried each one to its appointed coffin.

  The execution was a morning’s entertainment lasting four hours. Mydlár killed them all, using four different swords to make sure that the edges remained sharp. All in all, he beheaded twenty-four men and hanged the remaining three. Two he hanged from the town hall window, set up specifically for that purpose. The last he hanged from the gallows erected at the center of the town square. When all was over, they gathered the heads separately and chose out twelve special ones that once belonged to the more famous Protestant leaders, jammed wooden pikes through the medulla into the brain, and fixed them to the Stone Bridge so that people could laugh at them and be afraid as they passed the cornice of the bridge tower. At least the skulls were neatly arranged. Six faced the Catholic Church of the Holy Savior, and the other six faced Mala Strana across the river, so that all of Prague, on both sides of the river, could have a fair share of death. As an added entertainment and a grisly message, they nailed the severed hands, the right hands only, of Count Šlik and Dr. Hausenšild to their own skulls.

  One of the men executed that day, whose head also ended up on the Stone Bridge, was Johannes Jessenius, rector of Prague University and a friend of Johannes Kepler. Generally a man of peace and Christian virtue, Jessenius was the man who had negotiated a truce between Kepler and Tycho Brahe. Before cutting off his head, Mydlár also cut out his tongue. This was usually a symbolic act done to those who had sinned against the king with their mouths, and most often it was done after the man was already dead. However, in this case Ferdinand specifically reversed the order and insisted that Mydlár cut out Jessenius’s tongue while he was still alive. Apparently, the emperor reserved a special hatred for him, because he had tried to bring order to the Protestant cause and had orchestrated several peace negotiations among the distrustful Bohemian Estates. Instead of burying his body, the emperor had his headless corpse cut into four pieces and impaled on posts over a gate leading out of the city. The emperor then ordered Jessenius’s head to be one of the twelve chosen for impalement on the bridge and ordered his tongue nailed to his skull.

  The heads remained there for nearly ten years until 1631, when the Protestant Saxons entered Prague and a group of Bohemian émigrés, returning to the city, removed the heads from the tower and carried them to Tyn Church, the same church that held the bones of Tycho Brahe. According to legend, twelve ghosts rise from the dead every year on the anniversary of their execution to see if the hands of Master Hanus’s astrological clock were still moving, for everyone knew that when that clock ceased to run, the world would end and the Last Judgment would begin.

  KEPLER ARRIVED IN LINZ on December 22, 1617, just before Christmas. He had been to Leonberg to try to settle his mother’s affairs, but Einhorn had managed to delay Katharina’s lawsuit against the Reinbolds one more time. The Christmas season was on, and each family in Linz was preparing itself for the birth of Christ. Families gathered, sang songs, told stories, drank too much, and ate too much. In Kepler’s household, however, there was only sadness and death. It was not much of homecoming—two of his little children by Susanna had already died. Now, little Katharina, named for Kepler’s mother and just a baby, was deathly ill. As in Graz, Kepler descended into a morbid depression, while thoughts of death choked him. He tried everything to save her—doctors, herbal cures, prayers to heaven, but nothing worked. By February 9, little Katharina’s fever had overcome her, and she died. Oppressed by sadness, Kepler could not even find solace in his work. He could not work on the Rudolphine Tables, for in his grief he found the calculations too tedious, the work too hard. “Because the Tables require peace,” he wrote to a friend, “I have set them aside. I am turning my thoughts back to the Harmony.”5

  By all human reckoning, the previous five years of Kepler’s life had been lived in the seventh level of hell. His own church had excommunicated him on a technicality, and Pastor Hitzler’s sinful misuse of Kepler’s confidentiality had threatened his reputation and even his livelihood. His mother had been vilely accused of witchcraft, and when she sought justice, she received the worst kind of bureaucratic manipulation. The Kepler family was beginning to suspect that old Katharina was in serious danger. Kepler too had been accused, but they couldn’t make it stick. And finally his children, one after the other, had died of some traveling pox. By all human reason, he should have been a broken man, but, instead, he turned back to his Harmony of the World, a work dedicated to the belief that the universe is finally good and ultimately beautiful.

  Loss and suffering, however, dressed him in the morning and tortured him at night. If only their church had not set them adrift, for even if God had not failed them, the Lutheran church of Württemberg had and failed them deeply.

  The Lutheran consistory, clouded with orthodoxy, had denied his appeal after Pastor Hitzler’s excommunication. On his trip to Swabia, Kepler had tried to reconcile himself with Matthias Hafenreffer and the church, but failed. His enemies, hidden in shadows, had conducted a whispering campaign, accompanied by secret letters between them and members of the consistory. Their opinion of Kepler was not very high. In 1619, a year after the consistory’s decision, while the witch trial was still under way in Leonberg, Erasmus Grüninger, one of the members of the council, wrote a letter to Lukas Osiander, then superintendent of the Tübingen seminary, defending their handling of the case, saying: “Touching on this Kepler, we have long had dealings with this crazy man, but to no avail, because he would not listen to what anyone else says. We [of the consistory] did not want to keep silent with the worthy faculty of Tübingen, about what the consistory had written to him years ago on this subject [of his excommunication], because we felt that the faculty would likely have dealt with him the same way, since not one of us would want to change his beliefs just to please Kepler’s sick head.”6

  Was this pique at some former student who had dared to deviate from orthodox Lutheranism? No, it was more than that, far more, for Kepler had committed the unforgivable sin—he had warned them of the fire to come. He had played the prophet against them, played Jeremiah predicting disaster to Jerusalem, disaster for them and for all of Germany because of their refusal to treat other Christians with Christian courtesy.

  Württemberg was a provincial place, a big small town. Although some of the church leaders had traveled outside the duchy and some were even cosmopolitan in their way, few had ever seen Europe as Kepler had. Few had stood in the halls and courtyards of Prague Castle or attended the emperor—three emperors to be sure—or had kept up a steady correspondence with kings, dukes, princes, and bishops, as Kepler had. Few of them had ev
er suffered eviction for their faith or struggled with the dark night as Kepler had. For them, the events in Graz or Prague or Linz were the substance of reports from far-off mission lands, abstract in a way, foreign and dreamlike, something to be clucked at over beer and sausages. Kepler, however, had seen the reality from the front, had watched the storm clouds of war piling ever higher, starting small in Graz and then spreading with the ever rising power of Ferdinand of Habsburg, the arch-Catholic and protector of the Counter-Reformation. Kepler had seen it all, and knew what was coming.

  The threefold split in Christianity, like a festering wound, would have to be cleaned of putrefaction, he wrote to Hafenreffer, and cauterized by the fire of war. He could see it coming, but they could not. In his letter to Hafenreffer, Kepler had written: “Then suffering will give you insight over many things, things that you conceal from your students who are even now growing up in the service of the church.”7 War is coming. Be prepared.

  He was right, but they could not see. Not wanting to play the heretic before his family and his numerous friends, Kepler finally wrote down all of this, setting forth his beliefs about the relations between the churches, explaining his theological opinions, and defending himself against all the talk that surrounded his excommunication. The pamphlet, published anonymously in 1623, and titled A Profession of Faith and Defense Against Numerous Unjust Rumors Which Arose Because of It, circulated among his friends and relations. Things quieted down for a while then. Two years later, however, the conflict caught fire once again, and the consistory, never squeamish about privacy, published Kepler’s last letter to Hafenreffer to show that they were of one mind against him. Kepler then revised his pamphlet and republished it, this time for the public. He responded in footnotes to each of the points raised by his letter and set out his true beliefs and precisely reasoned opinions.

  Meanwhile, the Counter-Reformation stood nearby like carrion birds, with the Jesuits ready to gather in another convert. But they too would find Kepler a difficult fellow. His beliefs were his own, and he would not surrender them to either pope or consistory. His faith was in God, divinely unaffected by human theology, while the stars danced across the sky, waltzing to their own music, stately and perfect, far above the discords of earth.

  In his life, Kepler wrote three great cosmological works—the Mysterium Cosmographicum, The Mystery of the Universe; the Astronomia Nova, The New Astronomy; and the Harmonice Mundi, The Harmony of the World. The last of these, his book on world harmony, he began soon after being forced out of Graz, while he was still working on the Astronomia Nova. The idea of harmony was a perfect blend of philosophy, astronomy, music, and theology.

  But the Harmony had been coming a long time and was the culmination of a number of lesser works. During the years he lived in Linz, Kepler suffered so much from his struggles with the Lutheran church that he often had difficulty jumping back into his astronomical studies. Instead, he finished a series of projects that had been sitting in the back storeroom of his brain for a number of years, starting as far back as 1600, the terrible year he fled Graz to take up employment with Tycho Brahe in Prague. Among these was a series of short works on odd questions, most notably his method to measure the inside of a wine cask. He also wrote his Epitome Astronomiae Copernicanae, his textbook on Copernican astronomy, modeled quite consciously on the Epitome Astronomiae, the famous textbook on Ptolemaic astronomy by his old master Michael Mästlin.

  The story starts as far back as 1613, the year that Ursula Reinbold claimed to have taken her fateful drink of potion. During the heat of the summer, Kepler had traveled from Linz to Regensburg to meet with Emperor Matthias and to answer several astrological and astronomical questions. Coming home, he traveled by boat down the Danube River, as he often did, and along the way he noticed that there were wine casks lashed together in various places along the shore. Each cask was a different size and shape, because barrel making was a craft and each piece was made one at a time. Typical of Kepler, his mind quickly recognized in this a new mathematical problem. How can one calculate the interior volume of a wine cask? Remember that integral calculus had not yet been invented, and so Kepler was trying to a find a way to describe a curved surface with precalculus mathematics. In doing so, he created the basic theory behind calculus by imagining a number of thin discs of varying sizes, stacked in such a way that they would exactly recreate the interior shape of the cask. If you could calculate the area of each disk and calculate how that area changed as you moved down the length of the barrel, then you could add up the areas and have the volume of the cask.

  Again typical of Kepler, he tried to find some way to generalize this new method. He started by describing shapes produced by conic sections—the circle, the ellipse, and the parabola—that were rotated around a single line on a plane, thus creating a solid shape. In taking slices out of each conic section, he could thereby reproduce the shape of the rotated three-dimensional object. What Kepler had done was to set the imaginative beginnings of calculus, which was later formulated separately by Newton and Leibniz. He developed his new method into a short book—the Nova Stereometrica Doliorum Vinariorum, or A New Stereometry of Wine Casks.

  Kepler couldn’t find a publisher for his new work, so he took a lesson from Tycho Brahe, invited the printer Johannes Planck to come to Linz, and sent the manuscript to him. The book finally came out two years later, in July 1615. Even though the Stereometria was the first book ever published in Linz, Kepler’s bosses at the school and among the representatives of the Estates were not overly thrilled by it. A book on measuring wine casks was not quite the work they had in mind for him to do. It didn’t seem as noble as the Rudolphine Tables, which were based on the great work of Tycho Brahe and dedicated to the emperor. And well, they just didn’t understand what Kepler was doing. Measuring wine casks was mundane, to be sure, but finding newer and simpler ways to measure curved surfaces was not.

  In the process, however, Kepler learned something about publishing. He was not as rich as Tycho Brahe, who could afford to run his own press and could therefore produce a small print run of his esoteric works simply to publicize his ideas. But Kepler could still do something of the same sort, if on a lesser scale. He purchased his own set of printer’s type and even ordered some mathematical symbols to be cast to round it out. This type set was the most precious thing he owned, and since he was sliding sideways into the publishing business, he had to try to make some money along the way. Kepler had already learned, as far back as the Astronomia Nova, that his books were not best-sellers, because few people could understand his complex mathematics or appreciate his methods. He was not the satirist that Galileo was; he just did not have the flair for controversy. But he had learned that he could make money by printing presentation copies to be given as gifts to important members of the nobility, for which they always returned a comfortable stipend. Kepler found that he could make more money on the presentation copies than on the regular sales.

  With his Stereometry, he had ordered both a Latin and a German version printed, so that he could cover a wider circle of the nobility and thereby collect more stipends. When all was done, after he had given away all his gift books, he had made enough money to pay for the printing costs and even pocketed an extra 40 florins. After listening to the three emperors’ empty promises for so many years, Kepler had finally decided to go commercial, and in the case of small-print-run books, that meant getting them into the hands of the people with the money.

  Holding his intellectual nose, he also began to publish his yearly astrological calendars once more, after a hiatus of eleven years. The first of these new prognostications came out in 1616, and though Kepler looked down on his own astrological work, saying that it was “only a little more honest than begging,” he had learned that if he wanted to do great works, he had to support them with his astrological penny stinkers, which were much more lucrative.

  Kepler had also discovered, as far back as 1611, that terrible year, that if he ever wanted his
ideas to reach a larger audience, then he would have to write his own textbook, his own Epitome. In this book, he would not only explain Copernicus’s theories to the educated masses, but his own as well. His old teacher Michael Mästlin had been the rock star of astronomical textbook authors in Germany with his Epitome Astronomiae and had made some decent money in his time. Though Mästlin had introduced Kepler to the Copernican universe, his own textbook had done one of the best jobs of explaining the Ptolemaic universe. Kepler’s own textbook, the Epitome Astronomiae Copernicanae, or Epitome of Copernican Astronomy, took off from Mästlin’s book and did for Copernican astronomy what Mästlin had done for the Ptolemaic system. He gave Planck the manuscript for the first volume of the Epitome in May 1616.

  Then at the end of 1617 he wrote another prognostication for the year 1618, and then another for 1619. His calendar for 1619 took a shot at the Württemberg church. “I know a gelding animal that sits among the roses, covered in majesty, and stares out at its enemy, that other animal, without fear at all, though its enemy will soon cause its death. Be careful, therefore, get ready for the stroke, stop shoving and remember that you are here for the sake of the milk, not for your own benefit.”8 Suddenly Kepler was a prophet. Everyone wondered who the gelding animal was; some wrote to Kepler, some stopped him on the streets, begging him to let them in, to tell them the secret. Many of them thought he was talking about the pope; others about the House of Habsburg; others about the Jesuits or even the Rosicrucians. Kepler never explained himself, however, for he knew that those he addressed his message to, the consistory in Württemberg, already understood him well enough.