A GOOD DEAL of the pleasure of almost anything comes from knowing something about the subject. Whether it be golf, opera, or ecology, there isn't much fun in groping around in the dark and jazz is certainly no exception. For a long while writing on the subject of jazz was pretty much in the polemic class on the one hand or the tract class on the other. The books were mostly written by people who devoted 300 pages to proving that one or the other periods in jazz was the real thing and all others merely a plastic image of the good stuff. It was usually possible within the first ten pages of reading to tell what particular jazz ax the author was about to grind for the next ten chapters or so and the worth of the book was judged only by the critical biases of the individual reader...