The Astronomer and the Witch: Johannes Kepler’s Fight for his Mother 
by Ulinka Rublack.
Oxford, 359 pp., £20, October 2015, 978 0 19 873677 6
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In autumn​ 1937 a statue of Katharina Kepler was unveiled in Eltingen, the village near Stuttgart where she had been born three centuries earlier. Barefoot, wearing a shift, sickle in hand, she represented the ideals of rustic nobility and honest toil cherished by the Third Reich. The mayor said that Frau Kepler also stood for the determination to uphold truth in the face of persecution: accused of diabolism, she had resisted. The ‘witch craze’ of the 16th and 17th centuries was a subject that appealed to the Nazis; Himmler set up a historical research department to look into it. German witches were seen either as innocent victims of ecclesiastical oppression, völkisch heroines for an anticlerical dictatorship, or as degenerates, justly exterminated in a campaign to purify society.

Ulinka Rublack’s book about Katharina Kepler, and her son’s extraordinary defence of her, is fine-grained microhistory, but it’s also revealing of the larger ideas that framed their world. There was a kaleidoscopic array of opinion about the substance and operation of the universe. In this context how could the crime of witchcraft be proved? Was it even possible? Eighteenth-century philosophers lumped together fanatical demonologists and peasant mobs, the better to compare a benighted past unfavourably with an enlightened present. In reality, people from the top to the bottom of the social order displayed doubting, discerning tendencies. Superstition and science, rather than being successive stages in the ascent of reason, co-existed so closely and dynamically that the definition of neither is reliable. The Astronomer and the Witch illustrates this complexity, and its transitions, with agility and sensitivity.

In the Austrian town of Linz on 29 December 1615, Johannes Kepler received devastating news. Three months earlier, his mother’s neighbours in Leonberg, a walled town in the duchy of Württemberg, had accused her of inflicting sickness on them using witchcraft. Lutheran pastors preached that witches could not cause harm, and that only the devil, with God’s permission, wielded such power; but there was no agreement on this point. Katharina had sued for slander, but her opponents belonged to a powerful faction which was after her blood. As a 68-year-old widow of modest means and status, she would need all the help she could get to avoid the fate of a convicted witch.

Her son had come up in the world. He was 44, a gifted scholar from peasant stock who had won a place at Tübingen University to read theology. Even with a scholarship, the cost to his family had been great: they could not afford for Johannes to study law, and his grandfather had pawned a meadow to support his studies. But the investment had paid off. Kepler soon found himself in the service of the Habsburg emperor, Rudolph II, in Prague, where he worked as astronomer and astrologer (they didn’t see the distinction that we do). From 1600 to 1612, the illiterate Katharina had corresponded with her son through a local schoolmaster.

Four days after receiving the bad news about ‘his beloved, aged mother’, Kepler wrote to the magistrate in Leonberg to plead for leniency. But he had to tread carefully. He had drifted from the Lutheran orthodoxy of faith in Christ’s real presence in the communion bread and wine towards a Calvinist belief in a symbolic presence. Tübingen shunned him for this dissent. Rudolph’s court had been a tolerant, freethinking haven, but since the emperor’s death in 1612, strict enforcement of Catholicism in the Habsburg territories had made it wise for any Protestant, Lutheran or Calvinist, to leave. Kepler had moved to Linz, where he found work as a teacher and cartographer. The University of Bologna offered him a proper job in 1616; Italy was even more dangerous than Germany for a Protestant. In the same year, the inquisition forced Galileo to recant his geocentric heresy, an idea which Kepler endorsed.

Most witchcraft trials occurred not in the Middle Ages, but in Kepler’s lifetime, during the Protestant Reformation and Catholic Counter-Reformation. Witch-hunting can in part be explained by the fury of that schism. The war between Christ and Antichrist took many forms, including village squabbles where the wretched were suspected of bewitching the righteous for revenge and gain. The accused were typically women, usually older and dependent on their communities. Around 25,000 witches were executed in early modern Germany, including 3200 in south-western regions between 1561 and 1670. Of these, only 197 (6 per cent) were in the duchy of Württemberg. This relatively reassuring information was not available to the Keplers, whereas the horrifying news of scores of people burned in Ellwangen, outside of the duchy but just sixty miles away – three hundred in 1611-12 alone – probably was. Johannes was right to fear the worst for his mother. The first to accuse Katharina was her own son, Johannes’s younger brother Heinrich. He had returned home from serving in the imperial guard, penniless, at a time of bad harvests, shortages and high prices, and had denounced his mother for failing to feed him properly. Rumours crept through the streets of Leonberg, and dark patterns formed in the minds of people who had suffered bad luck. Ursula Reinbold, who had recently become lame, said: ‘That Kepler woman has to take her spell away before I die.’

Opinion about the reality and prevalence of witchcraft, always finely balanced, now tipped towards credulity. In 1613 Leonberg had appointed a new ducal governor, Lukas Einhorn, who, as the food crisis deteriorated, began to take witchcraft accusations more seriously. It didn’t help that Reinbold was well connected, and able to arrange for the governor to call her alleged tormentor to account. The ensuing confrontation, in the summer of 1615, had prompted the lawsuit for defamation that Katharina lost and which now put her in even graver peril.

The winter of 1615 was intense. As people eked out dwindling supplies of food and fuel, and the poorest scavenged in the countryside, Einhorn stepped up his witch-finding campaign. In December, four women from a nearby town were beheaded in Leonberg; their ‘accomplices’ were tortured and executed the following spring. More accusations were made. Suspicions in other ducal towns were bruited about (where once they would have remained private), and hardened into legal fact (where once they might have melted harmlessly away). Katharina’s case stalled until October 1616, when Einhorn sent a report to John Frederick, the duke of Württemberg, detailing the accusations against her, which now included hurting children. Ducal councillors ordered the governor to detain the suspect. But Katharina had already left Leonberg to be with her son in Linz.

Katharina made the 300-mile journey, some of it on foot, the rest by boat down the Danube, accompanied by her youngest son Christoph, a master pewterer. It was another freezing winter, and by the time they arrived in Linz she was ill. With the support of a local pastor, Christoph petitioned John Frederick, emphasising his family’s respectability and the poor character (and inferior status) of Reinbold. She was promiscuous, he said, and used quack cures bordering on the diabolical. Another letter arrived at the ducal chancellery in the same month, January 1617, from Kepler, who pledged his loyalty and requested protection for his good name as well as for his mother’s life. Showing mercy, he implied, would reflect glory on his patron, the duke. It was a deft move, and a reminder that successful men of letters were astute politicians not ivory-towered dreamers. Kepler also complained to Württemberg’s vice-chancellor that the ‘storm’ was threatening to ‘shipwreck’ his life, and suggested that the best course of action was to ignore his mother: after all, she was just a silly old woman with a loose tongue.

Throughout the rest of 1617, Kepler had to deal with problems in his immediate family, including the deaths of his four children, while pushing ahead with his work. In September, Katharina returned to Leonberg. Kepler wrote to the duke blaming Einhorn for the social chaos caused by proliferating witchcraft accusations. Soon afterwards, he was allowed to take his mother back to Linz, along with her recently unfrozen assets. But it seems that Katharina remained in Leonberg for the winter, further antagonising Reinbold, who argued that there was enough evidence to prove her a witch several times over. A hearing took place in May 1618, and a commission was set up later that summer. But the wheels of justice turned slowly.

Proceedings began in Leonberg town hall on 9 November 1619. Reinbold’s kinsmen repeated their suspicions, further alleging that Katharina had driven her husband from her house; cast as a bad wife as well as a bad mother and neighbour, she was halfway to being a witch. The Keplers responded in kind, and the two sides dragged each other’s reputations through the mud: money, sex, lies, magic and neglect were the salient themes. There were 21 witnesses, including the schoolmaster who had written letters for Katharina when Johannes was in Prague. He now suspected that the wine she had thanked him with was poisoned.

The same year, Kepler published Harmonices Mundi, a treatise on the structural beauty of creation and the sublime relationships between its every aspect. Famously, it includes his third law of planetary motion; less famously, it contains a passage in which Kepler opened up about his mother. This is less incongruous than it sounds. As her son, he reasons, he must correspond to Katharina in nature’s grand scheme, and yet they also had to be different. At a deep psychic level this ambiguity between blood and breeding vexed him; but his reputation was at stake. He identifies in her the same restlessness that propelled his scientific investigations, while regretting that her ignorance provides only negative outlets for such energy. She ‘disturbs the whole of her town’ and ‘is the author of her own lamentable misfortune’.

Meanwhile, depositions taken for and against Katharina had formed a disharmonious body of material, full of contradiction and confusion. In January 1620 the file was sent to the chancellery at Stuttgart for consideration. The Thirty Years’ War had begun in 1618. People in Leonberg strove to make ends meet; begging and crime escalated; there was a flood of counterfeit coins. And, after a three-year lull, Einhorn resumed torturing and executing witches.

Early one morning in August 1620, Katharina was woken by her daughter Margaretha and told to hide. The duke’s men were on their way. They found her lying naked in a trunk and took her to prison, first in Stuttgart, then in Leonberg. For a second time, she was questioned in the presence of her accusers. A report was sent to the chancellery, which authorised Einhorn to torture her if she refused to confess. As a concession to Christoph Kepler, who had built up an honourable reputation in Leonberg, the trial was moved to Güglingen, five hours away by horse. Margaretha had written to Johannes as soon as their mother was arrested. He left Linz for Württemberg.

The trial was a protracted affair, lasting many months, the sessions episodic and inconclusive. Kepler often visited the noisy jail where his mother, now in her early seventies, was chained to the floor. As she had no teeth, she used a broken knife to cut food into morsels she could swallow whole. Whatever pity he felt for his mother, he was also repelled by her appearance, the marks of age as well as privation, and understood it might have contributed to the suspicions – along with the fact that no one had ever seen her shed a tear. ‘I have cried so much,’ she said before a judge, ‘that now I cannot cry any more.’

The defence case that Kepler put together in 1621 began by insisting that all evidence had to be available in writing, a pre-trial procedure enshrined in Roman Law. He grappled with the detail and volume of the witness statements, undermining them one by one. It was the sort of thing he was formidably good at. All Kepler’s work examined the properties of things, and made deductions from such properties. He also listened patiently to his mother in Güglingen prison, ‘as she described how it was normal to act in her world, how a Leonberg widow did widow-like things’.

Soon Kepler was ready. He laid into the opposition: the witnesses were too young, too hasty, too vehement. They were factious, blinded by hate, subjective. They were malicious and superstitious and immoral. The principal accuser, Ursula Reinbold, was wantonly deluded. Previously damning evidence dissolved back into the mundane contexts it had come from. And his mother, whose herbal cures had so spitefully been called sorcery, re-emerged as a God-fearing citizen who helped others. Her incantations were prayers, her spells pious rituals. Kepler even managed to dismiss the peculiar fact that Katharina had asked a gravedigger for her father’s skull: she had wanted it not for necromancy, but to have it made into a memento mori. These arguments, and their antitheses, were sent to law professors at Tübingen. In September 1621 they concluded that there were insufficient grounds for Katharina to be tortured, but she might be shown the instruments of torture ‘to frighten the truth out of her’.

Her interview with the torturer gave Katharina another opportunity to deny the charges against her. And this time she protested so dramatically – falling to her knees and beseeching God to intervene if she were guilty – that the confrontation not only failed to prove her guilt, but confirmed her innocence. After 14 months in chains, and six years in a harsh legal spotlight, Katharina was free. But she never recovered from the ordeal, and died the following spring.

Kepler​ never paid much heed to witchcraft, but not out of a desire to play down the charges against his mother or because he was a modern scientist at odds with the supernatural. Rather, he believed in a divine universe whose perpetual unfolding left little room for demons. His heliocentric scheme came from observation, but also formed an image of the Holy Trinity with God as the sun, Christ as the stars and the Holy Spirit as the intervening space. Kepler’s astronomy did not seek to disenchant the universe: it exalted the sacred in nature. A providential spirit inhabited all things, from geometrically exquisite snowflakes to soap bubbles blown by children to the mathematics of peasant dance steps. Fossils were discarded experiments in design. And not only had God created these cosmic wonders, he had blessed mankind with the power to decode and explain them. In medieval Europe, mysteries were meant to be mysterious and life’s trials punishment for original sin; even Lutherans took a dim view of human potential. Kepler’s brave new world, by contrast, was formed by optimism and discovery and improvement. Worship was directed from the laboratory as well as the pulpit. ‘Instead of becoming a pastor with a parish,’ Rublack writes, ‘the Tübingen graduate turned himself into a priest of the Book of Nature.’ Seeing the pace of change in navigation, engineering, medicine, optics, and the sophistication and availability of printed books, ‘I really believe that at last the world is alive,’ Kepler said, ‘indeed seething.’

Witch-hunts tempt us to make something from history that never was: the self-congratulatory fables of the philosophes, or the twisted reports of Himmler’s Hexenforschung-Sonderkommando, or Eltingen’s statue of Katharina, or the fictional accounts of her life that either lionise or denigrate her (Arthur Koestler called her a ‘hideous little woman’). Yet the decline of witchcraft did not indicate medieval superstition surrendering to modern rationalism, not least because the transition was more contingent and protracted than we’re often led to believe. The years 1500 and 1800, terminal points of the early modern period, are joined not by a neat upward curve of progress but by a swirling pool of thought and feeling. For a long time, ideas that we may think of as ‘old’ and others we may think of as ‘new’ co-existed.

Once we accept this, it’s easier to understand how Kepler, like Newton, could be interested in spiritual communication and alchemy as well as ‘science’. These men weren’t secularist crusaders against an occult past: they were devout natural philosophers obedient to God’s wish for the universe to be explored by the creatures he had made in his own image. For Kepler to wonder whether an alpine hailstorm was a sign that he had angered a mountain by climbing it, or to see a cruciform bruise on his foot as an omen, was not a madcap aberration but an essential part of who he was, spiritually and intellectually. ‘Science had sprung from superstition in the first place,’ he said. Both stemmed from the desire to reach into a world of invisible forces to change the present and foretell the future.

It’s easy to associate the Scientific Revolution with the end of witchcraft trials; harder, perhaps, to connect it to their rise. And yet the meticulous assembly and analysis of data to confirm or confound hypotheses was a legal practice developed by inquisitorial tribunals at the same time as, or even before, the great strides made by Copernicus, Galileo, Kepler and others. Empiricism made witchcraft possible as an actionable crime before it made it an impossible one. Kepler saved his mother through formidable concentration, sticking to a firm line of reasoning and dissecting his opponents’ arguments, point by point. It was a trick he had honed in his early years as an iconoclastic astronomer, when it was crucial to maintain consistency in debate, and to anticipate objections so that they could be neutralised before they were even raised. Had he used the same methods to make the opposite case, he would have been the most prolific and terrifying witch-hunter that ever lived.

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