In 1627, officials in Cologne, Germany, accused Katharina Henot—a local postmaster and influential socialite—of witchcraft. They claimed she wielded magic, worked with the devil, and had infested a local nunnery with a plague of caterpillars. For these alleged crimes, she was repeatedly tortured and publicly executed. While extraordinary by today’s standards, Henot’s case was alarmingly common for the time. Between 1520 and 1700, Europe executed tens of thousands of people—mostly women—on charges of witchcraft. How did this happen? Surely anyone using science and reason could have deduced that such charges were ludicrous, right?