Dear fog, thanks for hiding the harmonica player on the Waterfront Boardwalk

On Wednesday evening the fog came in so thick on the Waterfront Boardwalk that I could not see the boats. Somewhere in the white a man began to play a harmonica, slow and slightly flat, a song I half knew. I stood there for ten minutes. When the fog lifted he was gone, but I could still hear it. I took the long way home on purpose. I have since identified the song. It is a lullaby. I do not know why he played it to the fog.