In 2007, a world-class violinist named Joshua Bell took part in a social experiment. The experiment was designed to understand how context shapes perception. Joshua Bell was one of the most celebrated musicians in the world. He played a $3.5 million Stradivarius violin. He regularly sold out concert halls. But that day, he stood in a subway station in Washington, D.C. He wore ordinary clothes. No announcement was made. No sign identified him. For 45 minutes, he played some of the most complex pi