It was a cold January morning in 2007. A man stood at a metro station in Washington DC and started to play the violin. He played six Bach pieces for about 45 minutes. During that time, since it was rush hour, it was calculated that thousands of people went through the station, most of them on their way to work. Three minutes went by and a middle-aged man noticed there was a musician playing. He slowed his pace and stopped for a few seconds and then hurried up to meet his sche