On this day, one of the biggest outbreaks of dancing mania began in Aachen and quickly spread to Cologne, Strasbourg, and even as far as Luxembourg and Italy. Dancing mania was a social phenomenon which occurred primarily in mainland Europe between the 14th and 17th centuries. It involved groups of people, adults and children, dancing erratically until, allegedly, they collapsed from exhaustion and injuries, and sometimes even died. Affecting thousands of people across several centuries, dancing mania was well documented in contemporary reports, but was, however, poorly understood, and remedies were based on guesswork. Some modern scholars believe it was a mass psychogenic illness, in which physical symptoms with no known physical cause are observed to affect a group of people, as a form of social influence.
