Commentary
Mass hysteria is the spontaneous manifestation of a particular behaviour by many people. There are numerous historical examples: Middle Age nuns at a convent in France spontaneously began to meow like cats; at another convent, nuns began biting one another. In 13th-century Germany, spontaneous dancing broke out and entire city populations danced until exhausted. But perhaps the best-known mass hysteria was the Salem Witch Trials, where people, seized by visions, accused others of bewitching them. Many were executed.
