The Theory of Heliocentrism

Right after Johannes Kepler put his ecstatic finishing touches on The Harmony of the World, the religious and political order around him began to break down completely. The period of decided disharmony into which his world was plunged is known to us as the Thirty Years War, one of the bloodiest periods in all of European history. By the time it was over, a third of the population of greater Germany would be dead. The one saving grace for Kepler was that he would not live long enough to see the worst of it.

It started in Kepler’s old home of Prague, a simmering stew pot of discontent ever since the death of Emperor Rudolf and the elevation of Archduke Ferdinand to the status of king of Bohemia. Ferdinand’s policy of forwarding the interests of Prague’s Rome-aligned Catholics at the expense of its Hussites, Protestants, and Jews was diluted only by his personal dislike for the city, which kept him away from it most of the time. Nevertheless, he left behind a board of five governors to slowly turn the screws, making life ever more difficult for Prague’s nonconformists. On May 23, 1618, the stew pot boiled over, when a Protestant mob attacked the absent king’s palace. By way of expressing their displeasure with the current status quo, the Protestants threw two of Ferdinand’s governors and one hapless secretary who had gotten mixed up in the scrum out of a window some 50 feet (15 meters) above the ground. Amazingly, all three men survived with only minor injuries, thanks to a mound of manure that stood below the window; the Catholics pronounced its fortuitous presence a miracle of God, the Protestants a suitable metaphor. This so-called “Second Defenestration of Prague” — yes, there had been a first one, 200 years earlier — may have played out like a farce, but it would have deadly consequences for Bohemia and the rest of Central Europe.

This initial act of open rebellion inspired many more. The streets of Prague were plunged into chaos, as all of the city’s religions suddenly seemed to be fighting all of the others at once. But still Ferdinand stayed away. For Emperor Matthias, who had ascended to his throne at the relatively ripe age of 55, had at age 61 lapsed into a decline that gave every indication of being terminal. Ferdinand hovered around his cousin’s bedside in Vienna, anxious to be on the scene when Matthias passed away so that he could press his own claim to the imperial throne.

That event came to pass on March 20, 1619, just after Matthias’s 62nd birthday. Uniquely among the monarchical orders of Europe, determining the next Holy Roman Emperor was not, officially at any rate, a simple question of determining familial seniority; each new emperor was rather chosen by a board of “Electors” that was made up of the leaders of the various provinces that constituted the empire. When a son or younger brother was to hand, the Electors were usually little more than a rubber stamp, but when an emperor died without leaving behind either, as Matthias had, the result was furious politicking. Hardly was his cousin’s body cold then Ferdinand set off on a junket across Germany to shore up support for his candidacy. On August 28, 1619, at age 41, he fulfilled his fondest dream, when he was crowned Holy Roman Emperor in Frankfurt Cathedral.

The first pressing matter on his plate thereafter was the chaos in Prague, which was now spreading across Bohemia and into northern Austria. Under the command of Johannes Kepler’s longtime antagonist Daniel Hitzler, the Lutherans of Linz rose up and seized complete control of the town. They contributed to a Protestant army that was sent to besiege Vienna itself. Drunk on power, Hitzler formally excommunicated Kepler from the Lutheran Church, severing his last traces of a connection to any community of worship. Going forward, Kepler and his family could only pray on their own.

A fiery Austrian named Count Matthias Thurn, one of the ringleaders behind the Second Defenestration of Prague, became the inchoate Protestant state’s de-facto leader. Casting about for a more elevated blue-blood to give his movement the only form of legitimacy that applied in this time and place, Thurn hit upon Frederick, Elector of the Palatinate, a scattered group of small but prosperous Protestant territories in western and central Germany. An invitation went out from Prague, asking him and his wife to come east and become king and queen of a new Protestant Kingdom of Bohemia as well.

Frederick was an easily influenced 23-year-old who had actually just finished voting for the rabidly Catholic Ferdinand as Holy Roman Emperor when Thurn’s invitation reached him in Frankfurt. He wrote to his father-in-law, King James I of England, to seek the advice of the leader of what was arguably the strongest single Protestant state in Europe. James told him that this Bohemian adventure looked to be a bad business; he would be better off staying in Germany. But for once, the allure of power and prestige outweighed the council of others in Frederick’s internal reckoning. On October 21, 1519, he and his English wife Elizabeth arrived in Prague to assume their second throne. Mutually coddled from birth, the royal pair were utterly unsuited to the challenges that lay ahead for their would-be independent Protestant kingdom. Frederick was most interested in gardening; his queen Elizabeth liked most of all to throw lavish balls. Neither had much of anything in the way of fixed convictions when it came to politics or religion. The two weren’t even Lutherans; they were Calvinists, the same sect Kepler had been excommunicated for daring to sympathize with on just one esoteric point of theology. When Emperor Ferdinand, who had no shortage of convictions, turned his attention to Bohemia, it was a case of a man against children.

Ferdinand raised an army of battle-hardened mercenaries in staunchly Catholic Bavaria and sent it east. After relieving Vienna, it swept into Linz in the summer of 1620, scything through the town’s disorganized Protestant defenders without breaking a sweat. Hitzler and the other architects of the rebellion were thrown into a dungeon somewhere, never to be seen again. But even had Johannes Kepler been a more vindictive man than he was, the downfall of his persecutors would have brought him no joy. For now he was once again at the mercy of Ferdinand, the flesh-and-blood specter of uncompromising Catholicism that had been haunting him intermittently for almost 25 years. Already that fall, Ferdinand would chase the badly over-matched Frederick and Elizabeth out of Prague; they would spend the rest of their lives in exile in the Netherlands, having lost not only Bohemia but their previous holdings in Germany proper as the price for their defiance of history’s last truly formidable Holy Roman Emperor. Matthias Thurn escaped to Sweden, but a dozen of his fellow fomenters were not so lucky. They had their tongues cut out, were drawn and quartered, and then had their heads cut off and mounted on spikes on Prague’s Charles Bridge; they would remain there for ten years in mute warning, until they fell down one by one of their own accord.

Kepler had plenty to keep him up at night. As if rebellions and invasions and executions and excommunications weren’t enough, the Sword of Damocles hanging over his mother Katharina finally fell during that same summer of 1620, when she was arrested and criminally charged in her village of Leonberg with the practicing of witchcraft. Leonberg’s magistrate Luther Einhorn had collected 49 of “the most terrible and shameful articles” to bring against her. In addition to her crimes against Ursula Reinbold, who was still subject to “unspeakable agony” as a result of drinking her potion, and those against the young girl she had struck, who “is unable to work even now,” she was accused of having preached that “there is neither Hell nor Heaven, but if one dies, everything would be over, just as it is with the senseless beasts”; of having gathered in the forest with other witches to “enjoy much voluptuous pleasure”; of having permanently paralyzed one man and killed another with her stock of potions; of having disturbed the local livestock and made the animals leap fences and attack their owners; of having chased away her husband “with her witchly deeds, and thereafter he perished miserably in the war”; of having tried to bribe Einhorn to drop the case with a silver goblet (this charge was actually true). It may seem like pretty weak sauce for anyone raised on more lurid tales of witchcraft, but, again, it can’t be emphasized enough how seriously Catholics and Protestants alike took these things during the seventeenth century. Needless to say, Katharina’s relation to her recently excommunicated son Johannes did her cause no favors. (And vice versa, of course.) She was said to have asked the local gravedigger for a human skull, so she could fashion it into a macabre drinking glass for her equally godless son.

Johannes’s brother and sister, who had made stolidly respectable lives for themselves there in the Duchy of Württemberg, as a tinsmith and as the wife of a Lutheran pastor, seemed inclined to protect their reputations by giving up their mother as a lost cause. But, to his eternal credit, Johannes Kepler refused to abandon the mother who had never actually been much of a mother to him. He wrote to the duke of Württemberg, asking that he step in and delay her trial until he could arrive to defend her, as was his “God-given and natural right,” as well as asking that the trial be moved out of the legal district that included Leonberg, where the judges had been prejudiced against her by Einhorn’s relentless campaign of condemnation. In a sign that Kepler’s title of Imperial Mathematician still held some sway, the duke agreed to both requests: the trial was postponed for six weeks, and was relocated to the village of Güglingen.

On September 26, 1620, Kepler visited his mother in her prison cell there. Now 74 years old and quite likely not fully compos mentis, she was kept in chains in the dank and the dark. As a final insult, she had to pay the salaries of her two jailers herself. Understandably livid, Kepler wrote a series of furious letters to the authorities, but found that he had reached the limits of his influence. His mother was forced to remain festering in her cell while he embarked on his latest and most unexpected career transition of all, into the role of her defense attorney.

He proved disarmingly adept at his new job, for all that it brought him little happiness. His first clever move was to request that the case be conducted entirely in writing instead of via oral arguments, where passions were more easily inflamed and the letter of the law more quickly forgotten. There were two disadvantages to the written method: it was far more expensive for the defendant, who had to pay a fee for every document the judges deigned to consider, and it was extremely slow, a matter of charges and rebuttals moving back and forth at the eternally tortoise-like pace of bureaucracy. Johannes’s siblings, concerned about their inheritance, had the gall to complain to him about the money he was spending. But he ignored them, being more concerned about his mother’s predicament. He wrote hundreds of pages in her defense with his own hand, treating what he regarded as superstitious nonsense way more seriously than it deserved, even as he yearned to be contemplating the true wonders of God’s universe.

It went on this way for the better part of a year. In the end, being unable to conclude definitively from the arguments and counterarguments presented that Katharina Kepler was a witch, but feeling equally unable to conclude that she wasn’t, the judges ordered her to be subjected to territio verbalis: literally, “verbal terrorization,” the mildest form of torture.

And so, one year and two days after her son had first come to her in her cell, Katharina received a less welcome visit from the prison bailiff and a couple of his minions. They carried the withered old lady, none too gently, to the torture chamber, where there waited three judges, a scribe, and the burly torturer himself. This man brought out the tools of his trade one by one and told about their operation in loving detail while Katharina’s teeth chattered in fear. There were the strapado, the thumbscrews, the Catherine wheel, the hot irons, the rack, the water torture… the whole ingenious roll call of man’s inhumanity to man.

The torturer had been ordered not to use any of these fiendish inventions upon Katharina Kepler, only to show them to her — but, importantly, she did not know this. She bore up better than many a strong man might have, in spite of her advanced age and the year-plus she had spent in chains. In fact, she had the presence of mind to seize the initiative away from her tormentors. The scribe documented it as it happened.

She announced one should do with her what one would. Should one pull one vein after another out of her body, she knew that she had nothing to say. With that, she fell on her knees, said the Lord’s Prayer, and declared that God should make a sign if she was a witch or ever had anything to do with sorcery. Should she be killed, God would see to it that the truth came to light and reveal after her death that injustice and violence had been done to her, for she knew that he would not take his holy spirit from her, but would stand by her.

According to the peculiar notions of Medieval justice, which still largely held in the seventeenth century, Katharina’s refusal to confess, combined with the lack of a lightning bolt sent from the heavens to punish her hypocrisy, were enough to prove her innocence. On October 3, 1621, she was ordered to be set free. Luther Einhorn and her other principal accusers were charged ten florins for having wasted the court’s time. Her imprisonment and defense had cost the Kepler family many times that amount.

Katharina’s acquittal was tragically Pyrrhic in another respect as well: she emerged from prison in almost a vegetable state. It seemed that her ordeal with the torturer and her final brave protestation of innocence had drained the last dregs of spirit she still had in her. Fearful that she wouldn’t survive a journey back to Linz with him, Johannes delivered her to the house of his sister, who had rediscovered her Christian charity now that her mother had been acquitted, and was now willing to take her in; the proceeds from the sale of Katharina’s house would more than pay for her room and board. Katharina Kepler died in her daughter’s home six months later.

Johannes Kepler returned to Linz, where he watched the inexorable unfolding of a drama he had already borne witness to in Graz and Prague. The edicts came down from Vienna one by one, slowly tightening the screws on Linz’s Protestants. As always, Kepler looked for comfort in mathematics and natural philosophy, which he had come to see as humanity’s temporal savior from its baser instincts.

The contemplation of these things will lead the mind away from desire and the other passions, out of which emerge war and all other evils, to a love of tranquility and temperance in all things. The more anyone falls in love with mathematics, the more fervent will be his dedication to God, and the more he himself will make every effort to practice gratitude, the crown of virtues, so that he will join me in prayer to the merciful God that much more sincerely. Let him crush the warlike confusion, eliminate devastation, snuff out hatred, and venture forth to discover that golden harmony once again.

It was heartfelt, but also profoundly naïve. It wasn’t even working so well for Kepler anymore, to say nothing of his less intellectually gifted, less spiritually attuned fellow citizens. His last book, The Harmony of the World, had been published several years ago to scant notice, sadly confirming his own speculation that it might have to wait 100 years to have its importance recognized. This book would prove his last significant original contribution to astronomy. Now in his early fifties, he looked and felt like a much older man, ground down as he was by the weight of his cares. Sensing that he might not have many years left, Kepler turned to the piece of unfinished business that had been “tormenting” him for decades. After all his brilliant leaps of innovation and imagination, his final service to astronomy would be an almost purely clerical one: finally getting Tycho Brahe’s observational data, in some cases as old as Kepler himself now but still unsurpassed, into a published book that those astronomers who followed him could make use of. Kepler’s mind of odd twists and turns constructed a skewed analogy: Tycho was the father, but he was the mother, responsible for bringing their progeny into the world.

So, he set to work cataloging and tabulating, making and checking and rechecking thousands upon thousands of calculations without benefit of computer, calculator, or even slide rule. It was drudgery, but it was vital drudgery, and he did it well. Another of his children died, of smallpox this time, while he beavered away.

The axe fell for every Protestant in Linz but him on October 10, 1625, when Emperor Ferdinand issued a decree dismayingly similar to the one that Archduke Ferdinand had issued in Graz more than a quarter-century earlier. All of Linz’s Protestants must either convert or leave by next Easter — except for Johannes Kepler once again, whose title of Imperial Mathematician and ongoing work on the imperial project that was still known as the Rudolphine Tables protected him for the time being. Nevertheless, even Kepler had to suffer the indignity of watching the Inquisition ransack his home library, carting away several dozen volumes that were found on the Catholic Church’s ever-growing Index of Forbidden Books. He bent his back even more to his thankless labor, desperate to be done with this, his last great task in life, before a catastrophe derailed him in one way or another.

For catastrophe was becoming more and more the order of the day through much of greater Germany, as more spasms of unrest — the inevitable result of Ferdinand’s increasingly draconian anti-Protestant policies — spread over the land. A major peasant revolt exploded in northern Austria early in 1626. Atrocities ruled the day on both sides in vicious fighting that gives the lie to any notion of total war as a purely modern-day phenomenon. Imperial soldiers deliberately burned the peasants’ fields, their only source of food for the coming winter; the peasants burst into monasteries to torture the monks and rape the nuns. “What execrable stupidity forces these people to run into the middle of new fires when trying to escape old ones,” lamented Kepler, truthfully if ineffectually.

His book of the Rudolphine Tables was finally being typeset and printed. Mindful of the atmosphere of menace that hung like a fog over the streets of Linz, Kepler refused to let the handwritten manuscript out of his sight; he took it home with him every night from the printer, slept with it next to his bed.

On June 24, 1626, a Protestant peasant army — or rather a mob — attacked Linz. The gates were shut to keep out the rabble while the local imperial government waited for help from Vienna. The siege went on for two months, over the course of which virtually no food came into the town. Many of its people were reduced to eating horses and rats. Kepler and his family went hungry along with everyone else.

Protestant saboteurs periodically started fires inside the walls; these made a bad situation that much worse. One night one of the fires swept over the printer responsible for the Rudolphine Tables, leaving behind nothing but charred paper, white-hot metal type, and other bits of smoking rubble. Once the site had cooled, Kepler sifted painstakingly through the type until he found some special astronomical symbols he had had custom-forged for his book. On the one hand, his policy of never letting his handwritten manuscript out of his sight had had its wisdom confirmed. But on the other, the fire was yet another huge setback for the dream of making Tycho Brahe’s data accessible to everyone. With the 25th anniversary of Tycho’s death looming, the project seemed cursed never to come to fruition.

The siege of Linz was lifted on August 29, when the peasant attackers fled before an imperial army marching up from Vienna. The latter would spend the rest of the year chasing its quarry hither and yon, cutting a wide swath of destruction through the countryside wherever it went. The famine that followed that winter, the result of the hundreds of thousands of hectares of burnt or neglected crops, would kill more people than Ferdinand’s soldiers could manage — which isn’t to say that they didn’t labor strenuously to do their part for the cause of carnage.

Feeling older and tireder than ever, but still stubbornly determined to see Tycho’s data published, Kepler realized that he could no longer accomplish that task from the half-burnt, de-populated, depressed town of Linz. He wrote to Emperor Ferdinand, asking formal permission as his Imperial Mathematician to return to the Duchy of Württemberg to see the project through. He had heard that good printers were to be found in the town of Ulm, he wrote. Ferdinand or one of his flunkies sent a perfunctory reply: sure, go ahead.

In November of 1626, Kepler and his family boarded a boat, which carried them up the Danube River as far as Regensburg. There the river became unnavigable due to the encroaching winter ice. Kepler found temporary lodgings for his family and set off overland alone. Arriving in Ulm, he signed a contract with a print shop run by one Jonas Saur and handed over his custom-made set of astronomical type. Just as he had in Linz, Kepler kept the manuscript with him at all times as he closely supervised every aspect of its printing.

The book that had been mooted again and again only to fail to materialize again and again was finished at long last in September of 1627. The daunting folio of 538 pages was filled mostly with closely spaced tables of numbers, incomprehensible to the layperson but of incalculable value to astronomers and astrologers. For them, it was a book of magic, providing the means to know the positions of the Sun, the Moon, the planets, and 1000 different stars in the sky at any given time, from thousands of years in the past to thousands of years in the future. Whether you were a heliocentrist of the new school or a hidebound geocentrist of the old one, it stood ready to become your standard reference to the sky. This bizarrely belated culmination of Tycho Brahe’s life and work was the first book of astronomy that could be said to comprehensively supersede Claudius Ptolemy’s 1500-year-old Almagest.

Today, of course, the Rudolphine Tables have themselves been long since superseded, and are chiefly of interest for what they can tell us about Tycho Brahe, that prodigious Dane, and Johannes Kepler, that awkward, well-meaning German genius who spent his life in Tycho’s shadow. True to form, Kepler declares the book’s real author to be Tycho, the “Phoenix of astronomers,” on the title page. The ornate frontispiece shows a temple to the ancient Greek muse Urania, the divinity after whom Tycho named his fabled observatory of Uraniborg on his sorcerer’s island of Ven. Important figures in the history of astronomy, both ancient and more recent, are represented by the columns holding up the temple’s roof; Aristarchus is sadly missing, thus illustrating how little his ancient version of heliocentrism was remembered or credited. The two imposing columns in front are dedicated to Nicolaus Copernicus and Tycho, who are shown having a spirited discussion with one another. On the base of the temple, just to the left of a map of Ven, Kepler has dared to include himself, sketching away by the light of a candle next to a model of the very same temple. The image manages to be prideful and humble at the same time, just like the man himself. It recognizes the importance of his achievement in compiling and delivering the Rudolphine Tables to the world, but reckons not at all with the earlier, breathtakingly original strokes of genius that have caused him to go down in history as arguably the most important single astronomer of them all, deserving at the very least of a column of his own alongside those of Copernicus and Tycho. And missing completely from the tableau are yet two more deserving thinkers who have figured prominently in our story, Giordano Bruno and Galileo Galilei.

We shouldn’t blame Kepler overmuch for their absence; it can take decades, sometimes centuries, to figure out who and what in history really matter, a fact that he knew as well as anyone. “There will be few buyers, as with all mathematical works, especially in these times,” said Kepler of the immediate commercial prospects of his crowning literary achievement. He wasn’t wrong in his pessimism. He returned to Regensburg, reuniting with his family after yet another lengthy separation, leaving most of the 1000 copies he had had printed to languish for years in the backroom of Jonas Saur. No matter: he had taught himself to care more about his posterity than his contemporaries.

Still, he had one more duty to fulfill to his contemporaries before he could let his posterity make what it would of the Rudolphine Tables. On November 25, 1627, he left Ulm on another hard winter’s journey. This time his goal was Prague, where Emperor Ferdinand had temporarily set up court as a way of projecting his power into Bohemia, which was still being roiled by intermittent waves of Protestant rebellion despite the ten severed heads that looked down in warning from the Charles Bridge. Indeed, the conflict was continuing to spread; Denmark had now come in on the side of the Protestants, and there were rumblings that Sweden was about to do the same.

So it was that Johannes Kepler three years before the end of his life entered the presence of Holy Roman Emperor Ferdinand II, in the same audience room where Tycho Brahe two years before the end of his life had come to see Holy Roman Emperor Rudolf II. Age and stress had given Ferdinand an uncannily similar appearance to that of his dreamy cousin: the same bulbous eyes, the same jutting chin, the same gaunt frame. But, as befitted his status as a practical emperor very much concerned with this world, Ferdinand sat surrounded by courtiers and lieutenants rather than alone in an empty room. Much to Kepler’s surprise, he greeted the stooped, haggard-faced astronomer with warmth and graciousness. Three cheers for the Imperial Mathematician and the book he had finally finished! As a fit reward, Ferdinand promised Kepler 4000 florins and a professorship at a major university where he would be able to work closely with his astronomical peers, a form of fellowship that had persistently eluded him throughout his life.

Alas, it would elude him still. For it soon became clear that Ferdinand’s gifts were still conditional on the very thing Kepler had so adamantly refused to do throughout the two men’s long, ambivalent relationship: convert to Catholicism. “I have never left the Catholic Church,” Kepler answered, thus showing that his relish for playing the antagonist had not entirely left him. He was deliberately confusing the issue to make a point, referring to a universal community of Christ — “universal” being the literal meaning of “catholic” — rather than the institution that went under that name. With its emphasis on what made Christians the same instead of what made them different from one another, his was a vision of religious harmony that few others seemed to share, least of all the zealous and dogmatic Ferdinand.

This made Kepler a problem for Ferdinand. He had no great desire to disgrace or otherwise ruin the life of the Imperial Mathematician who had just dedicated a major book to him, but he had decided that he would only have Catholics — his kind of Catholics, that is — in his court, just as he hoped eventually to only have Catholics as subjects in his empire. An unexpected solution to his dilemma came in the form of Albrecht von Wallenstein, an imperial general whose strategic and tactical brilliance was widely acknowledged to rival that of Ambrogio Spinola of Spain. Kepler and Wallenstein actually knew one another; in 1608, as part of his duties as Imperial Mathematician, Kepler had cast Wallenstein’s horoscope, predicting that the then-25-year-old would “attain the high honors he seeks, along with great wealth.” At some level, Wallenstein had come to credit Kepler as the author rather than just the messenger of his subsequent rise, in that way that we humans so often have of doing. Instead of shooting this particular messenger, Wallenstein was inclined to help and honor him.

Although a Catholic himself, Wallenstein was less punctilious about matters of religion than his emperor. In Zagan, a town in the southwest of modern-day Poland which he had recently been given as a reward for his exemplary service, people could worship pretty much as they pleased. Wallenstein offered Kepler a house there and a salary of 1000 florins a year. All he had to do was cast Wallenstein’s horoscope for him whenever asked. It seemed like just about the best deal anyone had ever offered Kepler, a comfortable refuge where could forget about the temporal politics that had chased him hither and yon throughout his life. He and his family arrived in Zagan in July of 1628.

It would be nice to be able to write at this point that Kepler spent his last years in blissful retirement there, puttering about with his books and numbers. But sadly, the best I can do is to note this was the case for a while at least. Although his excommunication was not formally reversed, he was more or less accepted back into the bosom of the local Lutheran community, who were less concerned about doctrinaire niceties than their brethren in Linz had been. He and Susanna had their seventh and last child in Zagan — five of them lived past age five or so — to go with the two surviving children from his marriage to Barbara. He played the proud papa, fussing and preening over the marriage of his eldest daughter to an up-and-coming medical doctor. When he retreated to his library, he indulged himself by writing a fictional story called Somnium seu Astronomia Lunari (“The Dream, or Astronomy of the Moon”), about a man who travels to the Moon. Some have called it the world’s first recognizable work of science fiction, extrapolating as it does from the natural philosophy of the time to arrive at what struck Kepler as a plausible story line.

But then it all fell apart, as it always did for poor Johannes. In June of 1630, Ferdinand suddenly decided that the general upon whom he had heaped honor after honor had grown too big for his britches. The emperor abruptly dismissed Albrecht von Wallenstein and stripped him of most of his territories, including Zagan. The Counter-Reformation and the Inquisition descended upon the town soon after. Hard experience told Kepler that it would soon be illegal to be a Protestant in Zagan, just as it had become illegal in Graz and Prague and Linz. His salary too disappeared along with his patron’s good fortune.

Kepler was not in terribly good health at this point, suffering from gout and all of the other typical ailments of a sedentary 58-year-old scholar. Yet he felt he had no choice but to set out toward Vienna, where he hoped to recover at least some of thousands of florins in back-pay that he was technically still owed by the imperial government. With that money in his pocket, he might find a new place of refuge, perhaps as far away as England. But as it happened, he would never make it even as far as Austria.

On the cold, wet evening of November 2, 1630, Kepler rode an exhausted horse into Regensburg. Soaked to the skin, racked by a violent cough, he checked into an inn, whose kindly keeper cared for him as his condition grew worse and worse. The innkeeper found a Lutheran pastor to minister to him, but the man refused to perform the Last Rites when he learned of Kepler’s excommunicated status. Thus unredeemed in the eyes of his religion, if hopefully not those of his God, Johannes Kepler went to meet his maker on November 15, 1630.

He was buried quietly two days later. On his gravestone was etched a eulogy he had written for himself in Zagan: “I used to measure the heavens, but now I measure the shades of the Earth. Although my soul was from Heaven, the shade of my body lies here.” The fate of Susanna and the children he left behind in Zagan is unknown.

Not long after Kepler perished, the ever-spreading violence of the Thirty Years War came to Regensburg, when a Swedish army attacked the city. Kepler’s grave was destroyed in the fighting. Even in death, he couldn’t escape the foolish squabbles over religion that had hounded him throughout his life.

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