In the slipstream of the rise of New Musicology, focusing on the organ and on organ musicking invites to rethink fundamental musicological issues, departing from the insight that music exists in performance. As the art of improvisation has been kept alive for over several millennia by now among organists, it may be fruitful to start there. A proper way of analyzing this art form starts with describing what actually happens when the music exists, i.e. sounds, i.e. is created, while listening: Real Time Analysis.