THE Life of Richard Wagner, published in four volumes between 1933 and 1946, was Newman's magnum opus. Most reviewers considered the book to be a monument not only to Wagner—but to Newman—demonstrating his mastery of musical biography. For the book's publisher, Alfred A. Knopf, Newman's Wagner was ‘one of the great biographies of my period’ even though the book did not sell as well as Knopf had hoped. The Life of Wagner was a sympathetic and measured account of the composer's life and works, though this was not the case in some of Newman's earlier writings on Wagner. In A Study of Wagner (1899), Wagner as Man and Artist (1914) and Fact and Fiction about Wagner (1931), Newman was not the perfect Wagnerite. Although charmed by Wagner's music, Newman was at times extremely critical of Wagner's philosophical and political writings, anti-Semitism, and reputation for arrogant and manipulative behaviour. These books not only bring to light Newman's ambivalence about aspects of Wagner's career but demonstrate Newman's expertise on a wide range of concomitant issues in European thought, such as debates over the theories of the evolution of music.

John Deathridge has described Newman as ‘Wagner's most outstanding biographer’ and in the context of Wagner scholarship it is not difficult to see why. In the nineteenth century, for example, readers of British newspapers and musical literature had contended with fierce opposition to Wagner by the leading critics of the day, including Henry Chorley (Athenaeum, 1830–1866) and J.W. Davison (Times 1846–1879). Even though more judicious work on Wagner, by Francis Hueffer, for example, had been published in the 1870s, the largely anti-Wagnerian tide had begun to change, especially with such strong advocacy through George Bernard Shaw's The Perfect Wagnerite in 1898. Moreover, Newman's Wagner scholarship was more concerned with questions of continental aesthetics and historiography, and were more intellectually wide-ranging than what Chorley, Davison, Hueffer and Shaw had accomplished in their work in the previous twenty years. The Life of Wagner demonstrates Newman's close acquaintance with a vast European literature on Wagner—a familiarity unparalleled by many other British writers.