Johannes Kepler, a German mathematician, astronomer, and astrologer, wrote the laws of planetary motion, was appointed mathematician to the Holy Roman Emperor, and is considered the father of modern optics. But also… the son of a WITCH? It’s hard to believe, but Johannes Kepler put his career on hold and spent 6 years defending his widowed mother against charges of witchcraft.
What?
I came across the story by chance. While my daughter and I were stocking up at the local bookstore, a title caught her eye; she looked over her shoulder and said, “This book totally sounds like you.” Naturally, I grabbed it. The book, “Everyone Knows Your Mother Is a Witch,” by Rivka Galchen, views Katharina Kepler’s life and the charges against her through her eyes. And wouldn’t you know it, my daughter was right. The book falls right into my reading taste… Historical, a little funny, and both interesting and engaging.
After reading, I researched Kepler and his mother— Who was Johannes Kepler? What happened to his career after his mother was accused of witchcraft? And WHY was Katharina Kepler accused?
Who was Johannes Kepler?
As a child, the Keplers were of modest means, but luckily, their son Johannes showed real promise in school and was granted a scholarship to the Lutheran Stift (Seminary) in Tübingen. While his gift was for mathematics, Johannes felt his calling was religion. At Tübingen, he studied under famous German mathematician Michael Mästlin, who believed Copernicus’s theory that the sun was at the center of our solar system. Kepler wanted to prove that Copernicus was right, but in a way that followed religious doctrine.
“Nature is a book that the divine plan is written on”
His first book, Mysterium Cosmographicum, in 1596 laid out some of his ideas about the Universe. He developed calculations about the rotations of planets and the distances between them. But he wanted to go further. He wanted to prove that God’s hand was in the heavens. He worked in Prague under the Danish Astronomer Tycho. And when Tycho died, he inherited the notes and began working with them as an imperial Mathematician to the Holy Roman Emperor Rudolph II.
Harmonicae Mundi or Harmonies of the World, the Laws of Harmonics resulted from decades of work, combining principles of geometrical, musical, metaphysical, astrological, astronomical, and even the soul. Everything was related, and everything could be described in geometric terms with ratios. (this work influenced Galileo and Descartes, and Newton used it as well, leaving out the theology.) He also published the Epitome Astronomiae, which systematically describes astronomy, and the Rudolphine Tables, based on Tycho’s observations that predicted the location of the planets at any time.
Kepler, Mysterium Cosmographicum, Tübingen, 1596
Kepler saw the Christian Trinity as a sphere, interconnected and equal, in balance with nature. (The importance of the Trinity and the various disputes about exactly how it works is well documented in the book 381 AD by Charles Freeman. It really was a bigger deal than we imagine today.)
But we mostly remember Kepler for discovering the Three laws of Planetary Motion
1. The planets move in an elliptical orbit, with the sun as the focus.
2. The time necessary to traverse any arc of a planetary orb is proportional to the area of the sector between the central body and that arc (area law)
3. Harmonic Law- There is an exact relationship between the squares of the planets’ periodic times and the cubes of the radii of their orbits.
(I copied this verbatim from Britannica Johannes Kepler because I didn’t want to mess it up; honestly, it’s above my physics education level to explain.)
(Note– he didn’t call them laws then; he just wrote them up as ideas. And while we look at this and say… yes, the planet thing is obvious… and I vaguely remember the arc measurement thing from a wildly difficult geometry class, remember, he came up with these formulas and ideas without the help of your geometry teacher or the internet.)
While he worked on all these things, Kepler also calculated the birth year of Jesus Christ, worked out that the mood and tides were closely related, and explained HOW the telescope worked… which directly related to how human optics work. He explained the EYE. He coined the term “satellite”. And he formed the base of Integral Calculus (yup, his fault you had to suffer).
But… then his mother was arrested for Witchcraft.
Katharina Kepler
Widowed, Katharina raised three children, lost her husband to war, and now lives alone with her cow and herbs. In 1615, her abrasive nature made her a target for a local baker’s wife, Ursula Reinbold, who claimed that Katharina poisoned her after an argument and accused her of Witchcraft. At first, Katharina brushes this off. And countersues Ursula for making false accusations. But more and more witnesses come forward…altogether 24! (including one from her other son, Johannes’s brother!), with strange claims about the old widow. Suspicious behaviors like how she walked around alone at night, how she caused intense pain in the Butcher’s knee, marked a young woman with her touch, and that she asked the gravedigger if it were possible to put silver over a skull to make it a drinking vessel. (FYI. You can, but it isn’t dishwasher safe) Her younger son Hans also told a story of her riding a cow backwards and then roasting it. Rivka Galchen introduces chapters with reworked depositions from the original documents so you can see just how flimsy the accusations were.
Katharina Kepler Eltingen Harke, CC BY-SA 3.0 via Wikimedia Commons
Between 1560 and 1700, over 70,000 people were accused of witchcraft, and around 50,000 were executed. Half of them were in Germany… and ¾ of them were women. Katharina faced a very real danger of being put to death for her “crimes”.
When the accusations became serious, her son Johannes put aside his work and came to her defense.
It seems that Katharina got the same sort of judgment as the witch in the scene from Monty Python film “The Quest for the Holy Grail.” The villagers bring Lord Bedevere a woman they’ve accused of being a witch. “Well, how do you know she is a witch?” Bedevere asks. “SHE LOOKS LIKE ONE!” they shout.
The non-fiction book The Astronomer and the Witch: Johannes Kepler’s Fight for his Mother, by German historian Ulinka Rublack, covers the trial in a more scholarly tone, but Galchen’s “Everyone Knows Your Mother is a Witch” uses the source materials and declarations to weave a page-turning tale. In the book, Katharina is a strongly independent woman who lost her husband early. She also says exactly what she thinks and gives advice where perhaps it’s unwelcome. This nature makes her unpopular with some of the local villagers. (Honestly, I think it’s a trait among many German women of a certain age). Interestingly, she refers to her son as many mothers would, not with “awe” at his prestigious title… but as her son who should help his mama.
And she wasn’t merely locked up; she was chained to a dungeon wall and guarded by two men (all of which were financed by the sale of her home). Katharina’s troubles go on for years. An old woman chained to a wall with guards. Madness. During that entire time, Johannes Kepler acted as her lawyer, traveling across the country to use his influence to free her. The time and trial bankrupt Katharina and Kepler’s work suffers. After 6 years, she is finally freed to live with her daughter in 1622.
Kepler spends the rest of his life trying to pick up the pieces. He’s unable to find work. In 1627, he managed to get a new patron, Albrecht von Wallenstein. Kepler is sent to Sagen in Silesia, where Wallenstein built a printing press for him to print his papers. In exchange, Kepler wrote Wallenstien horoscopes (oddly, he was fairly close at predicting Wallenstiein’s death). Johannes Kepler never collected all the money he was owed for his work before his death a few years later, in 1630.
Shortly before his death on November 15, 1630, Kepler wrote the epitaph for his own grave.
“I used to measure the skies, now I measure the shadows of Earth.
Although my mind was sky-bound, the shadow of my body lies here.”
Read more about Kepler and his Mother here
The Astronomer and the Witch: Johannes Kepler’s Fight for his Mother
Everyone Knows Your Mother Is a Witch
Resources
Everyone Knows Your Mother is a Witch by Rivka Galchen
I read and enjoyed Every One Knows You mother is a Witch. Thanks for the recommendation!
Glad you enjoyed it too!