In July of 1518, a woman began a fervent dancing vigil that lasted between four and six days. By the end of the week, 34 others had joined her and, “within a month, the crowd of dancing, hopping and leaping individuals had swelled to 400. Authorities prescribed ‘more dancing’ to cure the tormented movers but, by summer’s end, dozens in the Alsatian city had died of heart attacks, strokes and sheer exhaustion due to nonstop dancing.”