Over sixty years after his death in 1931, Vincent d'Indy is still a much misunderstood and maligned figure in French music. Previous biographers have left a portrait of the academic figure par excellence, who turned the seemingly inspired and selfless inspiration of his master Cesar Franck into a cold and authoritarian pedagogical system. This new study re-examines the evidence, reveals a much more psychologically complex and turbulent character, and finds that d'Indy was a tireless propagandist for a spiritual revival of French musical civilization. Yet he was fully aware of the social and intellectual problems of the secular Third Republic which militated against his Dante-inspired Catholic humanism, embodied in the work of the Schola Cantorum, the Paris institution founded by d'Indy to reform the practice of sacred music. Far from being a pure reactionary, his outlook was in reality remarkably progressive, manifest in his revivals of early music, notably Monteverdi's Orfeo, his encouragement of Debussy, and his willingness to engage - often pugnaciously - with the latest musical manifestations of Richard Strauss, Stravinsky, Schoenberg, and Varese. His own compositions likewise contain passages of astonishingly bold invention and modernistic effects, all too easily overlooked.