I don't think you can replaces great themes. But I think people do want to hear fresh arrangements of them. They don't want to hear them played the same way all the time.
“The first time I heard Johnny play at the Fillmore East, I wasn't really impressed. He had come on the scene with everybody telling me how great he was, and I didn't hear it.”
“The day is not far off when the economic problem will take the back seat where it belongs, and the arena of the heart and the head will be occupied or reoccupied, by our real problems - the problems of life and of human relations, of creation and behavior and religion.”