Tanner, a Cambridge philosopher and opera critic for the Spectator, offers analyses of the plots of Wagner's operas, the intellectual themes projected by them, and an evaluation of the music that is (for most of us) their justification. Tanner's discussion of The Ring is superb and makes an otherwise very uneven book required reading. He often overstates (arguing, for instance, that Tristan is one of the two great religious works in Western music, along with the St. Matthew Passion), and he generally loads his analytical dice to minimize or even delete Wagner's faults. While almost all serious music lovers include Wagner on their shortlist of the ten greatest composers, Wagner is for Tanner far more serious business than merely music. For him the purpose of his art is to change our lives. That makes his life very important, and Tanner's selective treatment of it is regrettable. Except for a mention in the four-page chronology, Tanner doesn't note the twice published Jewry in Music, Wagner's ferocious demand for racial purity in German music. This omission explains the comparative shallowness of Tanner's discussion of Meistersinger, which is described as a study of human folly, whereas from the outset it was recognized as a specific and passionate statement of German nationalism, and a work happily and repeatedly embraced by the Nazis. So why did Barenboim conduct Meistersinger at Bayreuth this year, and Levine at the Met? Because the incandescence of Wagner's music transcends his personality. As Rilke (another dreadful man and magnificent artist) noted, in attempting to explain the emotions evoked by Parsifal, it drives us ``to give joyous consent to the dreadfulness of life in order to take possession of the unutterable abundance and power of our existence.'' There is no question that Tanner, by fair means as well as foul, celebrates Wagner's power to achieve that.