Nathaniel Lew writes: John Bunyan's allegorical Christian novel The Pilgrim's Progress was a consistent and primary source of inspiration for Ralph Vaughan Williams. The composer knew the book's contents intimately, and returned to it repeatedly for a series of works that span much of his career. These include the 1922 one-act chamber opera (or 'pastoral episode') entitled The Shepherds of the Delectable Mountains, the 1940 anthem 'Valiant-for-Truth,' the incidental music to Edward Sackville-West's 1943 radio production of the book, and the full-length opera (or 'morality') completed in 1951, which in turn provided material for the Fifth Symphony of 1943. The incidental music composed for a community theatrical production of part one of Bunyan's book in Reigate, Surrey, preceded all these works and, despite its modest nature, served as a dramatic model and reservoir of musical ideas for them. It was also the source of the 1910 Tallis Fantasia.