Share(Read more.)Six-hundred and forty two years ago today, citizens in the German city of Aachen started to pour out of their houses and into the streets where they began to writhe and whirl uncontrollably. This was the first major outbreak of dancing plague or choreomania and it would spread across Europe in the next several years.To this day, experts aren't sure what caused the frenzy, which could drive those who danced to exhaustion. The outbreak in Germany was called St. John's dance, but it wasn't the first appearance of the mania or the last, according to The Black Death and The Dancing Mania, originally published in 1888. In the book, Justus Friedrich Karl Hecker imaginatively describes the spectacle of St. John's dance as follows:They formed circles hand in hand, and appearing to have lost all control over their senses, continued dancing, regardless of the bystanders, for hours together, in wild delirium, until at length they fell to the ground in a state of exhaustion. They then complained of extreme oppression, and groaned as if in the agonies of death, until they were swathed in cloths bound tightly round their waists, upon which they again recovered, and remained free from complaint until the next attack.