Autobiographical note: I was actually going to write about Chaos Magic (because a friend and I were discussing it, hockey and whether Durkheim’s definition of religion is too open to abuse and/or making a mockery of religion), but I couldn’t get it to come out right, so I’ll just link to it and you can read up on it as you please.
In July 1518 in Strasbourg, France, a woman named Frau Troffea inexplicably started dancing, and didn’t stop. Within a month, she was joined by 400 more dancers, many of whom eventually died of exhaustion, heart attack or stroke.
There are primary source documents to indicate that this was a legitimate occurrence, lest you doubt that 400 people were dancing manically and without stopping. The physicians’ notes, sermons and local reports are a boon to historians on the subject. The cause, however, is in question. At the time, it was believed that the people had drawn the wrath of St. Vitus*, who was said to deliver “plagues of compulsive dancing.”
The modern explanation of the events falls on two possibilities. The first is a mass psychogenic illness brought on by stress resulting from a widespread famine. The second is ergotism, a mild ergot poisoning. Ergot is a mold that grows on damp rye and consumption of the mold can cause delirium, hallucinations and seizures. However, historian John Waller suggests that the former is a more likely cause than the latter because ergotism causes a loss of blood to the limbs, which would make the afflicted move more like zombies (my word, not his) than dancers.**
*St. Vitus is, in modernity, the patron saint of dancers. And of Bohemia, which explains the gorgeous Gothic (and neo-Gothic…it’s a long story) cathedral dedicated to him (and apparently St. Wenceslas and St. Adalbert) in Prague.