Of all the opponents that the legendary astronomer Johannes Kepler ever faced during his eventful life, the one he could never quite beat had to have been his own mother.
Born in 1546 in what is now Stuttgart, Germany, Katharina Guldenmann was, by all descriptions, an extremely headstrong woman who eventually alienated all of her family members with her harsh tongue. At least one historian described her as an "evil-tempered virago" who had never learned to read or write (higher education for women was unheard of in those days). That she was also the niece of a woman who had been burned at the stake for witchcraft may well have contributed to her ill-temper.
Much of Katharina's anger likely came from her disappointing marriage to Heinrich Kepler who, despite being the son of a prominent merchant and burgomaster, never lived up to her expectations. Whether his drinking started before or after her married Katharina, Heinrich seemed incapable of holding on to his share of the family fortune. When Johannes was born on December 21, 1571, Heinrich was a petty officer in the service of the Duke of Wurtemburg. Despite her son being a sickly child, Catharina apparently had no qualms about leaving him in his grandfather's care in 1576 when she followed Heinrich to the Netherlands after he took up a new post. Johannes barely survived an early attack of smallpox and had only just started school when his father and mother finally returned to their home in Wurtenberg. Unfortunately, a financial disaster occurring when Johannes was only five year old cost Heinrich what little was left of his family money. Leaving the army soon afterward, Heinrich bought a small tavern in Elmendiggen where Johannes and his two younger brothers were put to work as pot boys.
Despite their relative poverty, Heinrich recognized his son's intelligence and arranged to continue his education. On November 26, 1586, Johannes Kepler enrolled in a school in Maulbronn and became one of the Duke of Wurtemberg's pet students. He passed through that school and the University of Tubingen with distinction and graduated Master of Arts before he was twenty. Despite ongoing health problems, it was news from home that likely caused Johannes the most distress. Not only did his father's tavern fail, but Heinrich then abandoned his wife and enlisted in the Austrian army to take part in the war against the Turks. As for Katharina, she eventually managed to drive away the rest of her family with her harsh temper and Johannes made it a point to stay as far from her as he could.
For all that he lived in an era where there was little distinction between astronomy and astrology, Johannes Kepler went on to become one of the key figures in 17th century science. Along with Tycho Brahe and Galileo Galilei, Johannes Kepler became one of the fathers of the scientific revolution and his works, including Mysterium cosmographicum, Astronomia nova, and Harmonice Mundi are still revered as classics in the history of science. Whatever his fame as an astronomer, he was still highly sought-after for his astrological advice, which eventually got him into trouble with the Holy Roman Emperor, Rudolph II. He was also denounced by Church authorities for dethroning Earth as the center of the universe (much as they had with Galileo). Along with various family woes, such as the death of his first wife and several of his children, Johannes Kepler was continually being challenged over his scientific teachings and his final astrological calendar was publicly burned in Graz.
And his problems with his mother rarely went away. Ill-tempered as always, Katharina Kepler continued to upset her entire family and managed to develop a sinister reputation due to her supporting herself by dispensing potions to willing customers. Considering the state of medicine at the time (and the fact that the best doctors were completely unaffordable by most peasants), local "wise woman" able to provide herbal remedies for various ailments were common enough across Europe. Despite her aunt's execution for witchcraft, Katharina reacted angrily when a woman in her town accused her of attempted poisoning. Hiring a lawyer, she launched a slander case against her accuser. For reasons of his own, the lawyer that Katharina hired used various delaying tactics to stretch the case out for more than five years. Unfortunately, these delaying tactics led to the case being passed on to a new judge who had his own experiences with Katharina's sharp tongue. Knowing that the judge was prejudiced against Katharina, the defendant in the case filed a charge of witchcraft against her. Since this was a capital offense in Germany (and many other parts of Europe at the time), Katharina Kepler was imprisoned in July, 1620.
Under the laws then in place, a charge of witchcraft meant that Katharina was considered guilty until proven innocent. Refusing to confess also meant that the authorities were free to carry out "interrogations" (torture) until she confessed to her crime. Her family history, including an aunt being executed for witchcraft, must have seemed damning enough but the fact that her own son was a scientist who had been condemned by the Church for his teachings must have factored into the case against her as well. Hearing about his mother's sentence, Johannes Kepler came home from Linz to defend her. With the help of his university and his old friend, Christopher Besoldus, Johannes was able to prove that there was no real evidence against his mother (only the ill-will brought on by her caustic temper). Katharina was released in 1621 and immediately brought a new lawsuit against the woman who had accused her to cover the costs of her imprisonment as well as damages. Johannes Kepler had returned to Linz by this time, exhausted as ever from his dealings with his mother. Katharina continued the lawsuit until her death in 1622, defiant to the end.
As for Johannes Kepler, he only outlived Katharina by a few years. Although he still supported himself and his family by writing horoscopes and serving as a court advisor to the Emperor's court, he also distinguished himself with his astronomical works, including a major star catalogue, the Rudolphine Tables (published in 1627 at his own expense). Lingering problems with the Catholic Church and agents of the Catholic Counter Reformation placed him and his family in danger on more than one occasion (being the son of an accused witch may not have helped either). Although the Jesuits were unable to arrest him due to the Emperor's influence, they did succeed in having most of his library sealed. By the time of his death in 1630, he must have been exhausted by his lifelong battles. He was buried in Regensburg in Bavaria although his gravesite was later destroyed in the numerous religious wars of that era. The only memorial of his burial that remains is his own self-written epitaph:
- Mensus eram coelos, nunc terrae metior umbras
- Mens coelestis erat, corporis umbra iacet.
- I measured the skies, now the shadows I measure
- Skybound was the mind, earthbound the body rests
Johannes Kepler died nearly broke due to his inability to collect the royalties owed him. His wife and children would have been left completely penniless if not for the help of family members who published many of his manuscripts to provide them with income.
Ironically, Kepler's influence was fairly muted during his lifetime and some prominent scientists ignored his work completely. It was only after his death that textbooks based on Kepler's cosmology became widely available across Europe. His laws of planetary motion, now a standard feature in every introductory astronomy class, only became accepted when better empirical measurements proved their accuracy and Newton later included Kepler's work in his own Principia Mathematica.
Now universally recognized today as one of the greatest scientists who ever lived, Johannes Kepler's fame is as much a testimonial to his iron determination during his lifetime as it is to his scientific achievements. Did he inherit that fierce will from his outspoken mother? If so, the obstinate Katharina Guldenmann may well have had a far greater impact on the world than most people realize.