The witch trial of Katharina Kepler is one of the best-documented cases among the early modern German witch hunts. Scholars specializing in studies of her famous son Johannes know about this trial, but it is of secondary interest to them, a curious episode occupying perhaps a few paragraphs in a biography. Surprisingly, this trial has been virtually ignored in English-language narratives of the witch hunts.

Katharina Kepler, a sexagenarian widow, was first accused of being a witch by her second, mentally unstable, son. Shortly thereafter a neighbor told the governor of Leonberg, the town where Katharina lived, that the widow's witchcraft made her lame. Accusations began to multiply. The Kepler family sued the neighbor for defamation of character and lost. Their mother was incarcerated. Her son Johannes took up the defense, and in the end she was exonerated. Rublack does an excellent job of reconstructing the physical and social environment in which the Keplers lived. She makes use of Leonberg's ample municipal archives. Tax records for 1575, for example, show that the Keplers were of “middling wealth” (40), not among the poor, as is often assumed. Nor was the elderly Katharina an economic drain on her community: like other women in her position, she could support herself through “agricultural work, selling hay, and providing credit” (43).

On a larger scale, the duke of Württemberg was weak and battled with the estates over priorities, and he lacked control over the local governors. One of those governors was Lukas Einhorn of Leonberg. Though the town suffered from the common economic and social dislocations of the time, Rublack notes that it “avoided destitution on any significant scale” (75). Yet Einhorn initiated witch hunting and did not follow prescribed procedures when accusations emerged. In Katharina's case, the irregularities were present from the beginning. He was socializing with the neighbor when the accusation emerged; Einhorn responded by having Katharina brought immediately to his house for questioning, without informing the local court or conducting a formal interrogation. When the defense by other family members proved inadequate, Johannes acted. He temporarily relocated to Württemberg; he questioned his mother about her accusers and local conditions; he demanded all the documents be presented to him. He wrote a carefully crafted defense, discrediting the testimonies of each witness. But ultimately it was the contacts he gathered through his studies at Tübingen and years of involvement with various courts that exonerated her. Surprisingly, Rublack does not describe the dramatic denouement—when Katharina was shown the instruments of torture and threatened and she got on her knees to pray, not to the devil, but to the Christian deity.

Rublack meticulously explicates Kepler's defense. She distills Johannes's understanding of what caused his mother's situation to three elements: “enmity against his mother due to her social situation as widow, a new governor ready to act, and pervasive cultural fears of old women…. A towering intellectual, he had identified how the German persecution of witches worked” (128). She points out similarities between the defense and his work, “using words to resolve rival sets of hypotheses, to analyze motives and causes, and to engage in historical reconstruction” (126). This description fits Kepler's Epitome of Copernican Astronomy, the textbook detailing his astronomical discoveries that he had been working on the whole period he was involved with the witch trial. It was perhaps the most important vehicle for the dissemination of his ideas. Yet Rublack barely mentions it. Instead she focuses on a few sentences that deal with the limitations (not falsity) of astrology from his massive Harmony of the World, best known for revealing his third law, and on The Dream, a fictional work showing how the solar system would appear from the moon, as she tries to tease out the psychological underpinnings of his relationship with his mother.

Rublack brings to life the environment of a witch trial, showing its relationship to a family and the community. For those interested in German society and politics, families, the witch hunts, and Johannes Kepler, it is a worthwhile read.