This book covers the music of Coltrane, Mingus, Ornette, Cecil Taylor, late period Coltrane, Shepp, Ayler, Cherry, AACM, and Sun Ra. It is valuable as an historical text, since Jost gives good outlines of each musician's career (up to 1974, when the book was published). The German author Jost gives in depth descriptions of formal aspects of each musician's work, which is most interesting in the case of the composers whose work extensively involves the working out of musical structures. It is a very rational approach to a very complex subject. At times, I felt that the absence of discussion of political or spiritual aspects of the music was not a good thing, but it seems like Jost's goal was to discuss history and form for the most part. It's a view of Free Music from a Western point of view.