“Holy Ghost” is the first extended study of free jazz saxophonist Albert Ayler, who is seen today as one of the most important innovators in the history of jazz. Ayler synthesized children's songs, La Marseillaise, American march music, and gospel hymns, turning them into powerful, rambunctious, squalling free-jazz improvisations. Some critics considered him a charlatan, others a heretic for unhinging the traditions of jazz. Some simply considered...