If you find yourself thinking you aren’t a victim of fashion, maybe take another look. Yes, we can consciously train ourselves to resist trends through force of habit. We can declare our preferences and stand on principle.But we aren't consciously aware of what's happening in the hidden turnings of our brains. Maybe what we call the unconscious has more control over us than we would like to think.Inexplicable episodes of mass obsession and compulsion serve as disquieting examples. Mass panics and delusions tend to occur, argues author John Waller, “in people who are under extreme psychological distress, and who believe in the possibility of spirit possession. All of these conditions were satisfied in Strasbourg in 1518,” the year the Dancing Plague came to the town in Alsace—an involuntary communal dance festival with deadly outcomes.