“The Astronomer and the Witch” by Ulinka Rublack
Published in the Wall Street Journal, Jan. 26, 2016
Science, Sorcery and Sons
Kepler believed in witches. He probably even wondered about the potions his mother brewed. But when she was accused, he came to her aid.
More than 300 years after Salem’s famous trials, American popular culture remains preoccupied with the supposed witches of 17th-century Massachusetts and to this day, there are still believed to be witches living amongst us, using spells to make someone call you and putting hexes on people. But we do not hear much about the women accused of witchcraft across the ocean during the same period in Württemberg, Germany. In “The Astronomer and the Witch: Johannes Kepler’s Fight for his Mother,” Ulinka Rublack, a professor of early modern history at the University of Cambridge, introduces us to one of these witches, Katharina Kepler, who was tried in Württemberg in 1615-21.
Katharina was the mother of Johannes Kepler, a key figure in the Scientific Revolution that had begun to sweep Europe. In 1609, as court astronomer to Emperor Rudolph II of Prague, Johannes used the remarkable naked-eye observations of his predecessor Tycho Brahe to discover that the planets orbit the sun in paths that are elliptical-overthrowing the belief in circular orbits that had held since Aristotle’s time and strengthening the arguments for a heliocentric universe. Johannes was a deeply religious Lutheran whose scientific work was imbued with spiritual beliefs. He cast horoscopes, listened to the “music of the spheres” and understood the cosmos to be a living organism possessed of a soul. Like most people of his time, he believed in the existence of witches.
Witchcraft trials in Germany were family affairs. A woman prosecuted as a witch had to rely for her legal defense on her husband, if she had one, and on her brothers and sons, if she did not. Widows were frequent targets of such accusations, because their right to engage in commercial activities-denied to other women-gave them an independence that went against the social order. Many widows, including Katharina, earned money as healers, using strange herbs and incantations. People feared the power of these women.

Katharina’s first accuser was her own son Heinrich, a ne’er-do-well who had returned home after 25 years of fighting as a mercenary throughout Europe. Angered that she did not have enough food on hand to satisfy him, he “publicly slandered her as a witch,” as Ms. Rublack recounts, and died soon afterward. His comment would come to haunt the trial, which was prompted by a persistent neighbor of Katharina, who claimed that she had become lame after drinking one of Katharina’s potions. Once Katharina was charged, other disturbing facts came to light, such as her request that a gravedigger exhume her father’s head so that she could fashion the skull into a drinking vessel. Hearing this, even Johannes wondered if there was something to the allegations.
By quoting liberally from the documents written by Johannes and his other brother, Christoph, in defense of their mother, Ms. Rublack opens a window onto the workings of witchcraft trials in 17th-century Germany. We see Christoph impugning the reputation of Katharina’s main accuser by referring to her past imprisonment for “illicit sex” and Johannes blaming the growing number of accusations against Katharina on the fact that people generally disliked old women-especially disagreeable ones like his mother.
Ms. Rublack asserts that Johannes’s skill and status as a scholar uniquely qualified him to save his mother. This is an appealing conclusion, given our knowledge of the crucial role he played in the Scientific Revolution. But her account reveals that, for all his brilliance and stature, Johannes Kepler was just another son scrambling to prevent his mother from being burned at the stake. He had no special status in the proceedings, and the part he played simply underscores the utter unpredictability-and the terror-of witchcraft accusations. No one’s mother was safe, not even a court astronomer.
Around the same time 14 other women in Württemberg were accused of witchcraft, and six of them were also freed. The ones found guilty met miserable fates, including torture and being burnt at the stake. But the others who were freed didn’t have-and apparently didn’t need-a brilliant astronomer on their team. Johannes’s interventions seem to have been met with no more favor by the authorities than those of his brother Christoph, a pewter worker, who prevailed in moving the trial to a more advantageous location, or even those of their sister Margaretha, the wife of a pastor, who successfully advocated for Katharina’s transfer to a somewhat more comfortable prison.
It was, however, Johannes’s persistence in the face of interminable delays and obfuscations that won the day. In the final stage of the 6-year action, he wrote a lengthy document arguing that his mother should not be tortured. His plea failed to convince the ducal court’s advocate. Johannes had one more chance to save her, with a plea sent to the law faculty of Tübingen. Luckily, the six professors were more compassionate, concluding that, at 75, Katharina was too old to be tortured. Instead she would be shown the tools of torture in the hopes that it would “scare the truth out of her.” In the torture chamber, Katharina impressed the witnesses with her pious behavior. Within days she was released from her iron shackles and allowed to go home. She died six months later.
Katharina Kepler’s story is fascinating, but Ms. Rublack’s book will disappoint some. It is written in a shorthand style that might be appreciated by scholars familiar enough with the period to understand passing references to, say, “Baconian men.” Other readers may prefer James Connor’s 2004 book, “Kepler’s Witch,” which provides a livelier narrative redolent with details of life in 17th-century Germany.
What happened to Katharina Kepler is a morality tale about the dangers faced by independent, strong-willed and sometimes disagreeable women in Germany in early modern Europe. It is also a valuable reminder that the Scientific Revolution was made by men with deeply held spiritual, religious and metaphysical views, including the belief that there were witches all around them-even, perhaps, at home.