The literary sources of this work, its many links with Wagner's life and thought, its libretto, music and stage history, are all thoroughly examined. There is a full commentary, with extensive quotation, on the work's critical history, and finally, a fresh assessment of its place in the Wagner canon and of its unique quality as a music drama that is both modern and Christian. Full references, a bibliography and a discography are provided. A special chapter of musical analysis is contributed by Arnold Whittall.