This song is about Eddie Balchowsky. He was the handyman for a club in Chicago called the Quiet Knight. He was a concert pianist whose hand was shot off during the Spanish civil war and he became a morphine addict. He kicked the habit and became sort of an icon in the Chicgo music and art scenes in the sixties and seventies.
He never stopped playing the piano. When we worked at the Quiet Knight we would sometimes hang out and listyen to Eddie playing in the empthy main room. Duke was the immense white German Shepherd that guarded the club after hours.
They would ring a bell at last call to make sure everyone was out of the club before thay released Duke. Once a guy didn't make it out in time and Duke broke his arm. He and Eddie were buddies.