Does the rule, the concept, come first? Does a rule, an idea of form, come first, even before the informal, out of which form might be said to have been generated? How does an improvisation begin? From here you could ask two more questions: how does the entrance into a compositional song form begin? What are the social conditions for the form’s emergence? But you could also ask: How do we enter into an improvisation and how does the improvisation become recognizable (or does it ever become recognizable) as a work of art?