It was an old practice of jazz musicians to invent melodies to avoid having to pay publishing costs of playing other composers’ songs. This has its up sides and down sides. But it does encourage improvisation! I was about to play Cole Porter’s great song “Night and Day” when I thought I would like to improvise something for Mr. Porter, imagining that I would meet him and sit down and chat and trade stories and melodies. So I improvised this piece as an “intro” to his song - and as a message to t