Dancing mania (also known as dancing plague, choreomania, St John’s Dance and historically St. Vitus’ Dance) was a social phenomenon that occurred primarily in mainland Europe between the 14th and 17th centuries. It involved groups of people, sometimes thousands at a time, who danced uncontrollably and bizarrely. They would also scream, shout, and sing, and claim to have visions or hallucinations. The mania affected men, women, and children, who danced until they collapsed from exhaustion. One of the first major outbreaks was in Aachen, Germany, in 1374, and it quickly spread throughout Europe; one particularly notable outbreak occurred in Strasbourg in 1518.
Affecting thousands of people across several centuries, dancing mania was not a one-off event, and was well documented in contemporary reports. It was nevertheless poorly understood, and remedies were based on guesswork. Generally, musicians accompanied dancers, to help ward off the mania, but this tactic sometimes backfired by encouraging more to join in. There is no consensus among modern-day scholars as to the cause of dancing mania. The several theories proposed range from religious cults being behind the processions to people dancing to relieve themselves of stress and put the poverty of the period out of their minds. It is, however, understood as a mass psychogenic illness in which the occurrence of similar physical symptoms, with no known physical cause, affect a large group of people as a form of social influence.
Left to their own devices, people are healthy, and people with so-called mental illness are just trying to find their way back to their natural state.
But when the madman laughs, he already laughs with the laugh of death; the lunatic, anticipating the macabre, has disarmed it.