The scientist who took on the witch-hunters

Kepler, right, on a monument in front of the Griffith Observatory in Los Angeles (AP)

The Astronomer and the Witch
by Ulinka Rublack
OUP, £20

The postal service between southern Germany and the Austrian town of Linz was on spectacularly bad form during the last quarter of 1615. It took three months for a very important letter to reach Johannes Kepler. When it finally arrived on December 29, the contents devastated the famous astronomer. His mother Katharina, a widow from the little town of Leonberg, had been accused of witchcraft.

Kepler was already a celebrated scientist and he would go down in history for his laws of planetary motion and his identification of elliptical orbits. In many ways, however, his response to that terrible letter represented his shining moment. Over the next six years he would serve as his mother’s devoted and endlessly resourceful legal advocate.

In her superb study, subtitled Johannes Kepler’s Fight for his Mother, Ulinka Rublack suggests that Kepler was well placed to mount his mother’s defence. He had spent many years battling against the odds in his academic career – seeing off opponents and rallying support for his daring theories. He was used to a fight. His initial response was to seek a rational explanation for the irrational charges levelled at his mother – they included dispensing noxious potions and magically appearing through closed doors. Kepler produced a petition in which he itemised the likely motives behind the accusations.

First, Katharina had struggled as a widow with young children, standing up for herself when necessary. She was in her seventies now, but disgruntled neighbours could have long memories. Second, something of a witch craze was raging in the duchy of Württemberg, so perhaps Katharina was just one more innocent victim. Finally, Kepler noticed that it was often the young who launched charges of witchcraft against the elderly: “quickly to the stake with the old woman” had become a familiar rallying cry, but this had more to do with cultural tensions than a genuine attempt to expose evil-doing.

Brilliant as this analysis was, it made no impact and a series of trials, interrogations and a “mish-mash of contradictory evidence” ensued. The stress provoked rifts within the Kepler family and Johannes struggled to continue his scholarly duties – though, extraordinarily, he managed to produce some of his most important work during this period.

Matters came to a head in 1621. The crucial question was whether Katharina should be subjected to torture. Again, Kepler’s intellectual powers surfaced and, this time around, they saved the day. He insisted on a specific legal procedure in which all evidence had to be presented in written form. This played to his strengths and he wrote a point-by-point refutation of the charges against his mother. The court documents went off to the legal faculty at Tübingen and the academics settled on a compromise. Katharina was to be shown the instruments of torture in a final attempt to “frighten the truth” out of her but no actual torture was to be applied. Katharina easily survived this lesser ordeal and was set free. Tragically, she was dead within six months.

Kepler is the hero of this story and he has some wonderful moments. Katharina wanted to take possession of her father’s skull. So what, said Kepler: she planned to set it in silver as a reminder of mortality.

Katharina emerges as an impressive figure, too. At one point a judge wondered why she refused to weep under such harrowing circumstances: “If you have a pious drop of blood in you, then let your eyes flow.” Katharina’s reply was dignified: “I have cried so much that now I cannot cry any more.”

As Rublack writes, Katharina “did not want to comply with men’s ideas of when and how she should express emotion”.

The author wanted her book to provide a “better understanding of individuals, but also of families, a community, and an age”. It succeeds triumphantly.