A man sat at a metro station in Washington DC and started to play the violin; it was a cold January morning. He played six Bach pieces for about 45 minutes. During that time, since it was rush hour, it was calculated that 1,100 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 musician playing. He slowed his pace, and stopped for a few seconds, and then hurried up to meet his schedule.
A minute later, the violinist received his first dollar tip: a woman threw the money in the till and without stopping, and continued to walk.