Whilst E.T.A. Hoffmann (1776-1822) is most widely known as the author of fantastic tales, he was also prolific as a music critic, productive as a composer, and active as a conductor. This book examines Hoffmann's aesthetic thought within the broader context of the history of ideas of the late-eighteenth and early-nineteenth centuries, and explores the relationship between his musical aesthetics and compositional practice. The first three chapters consider his ideas about creativity and aesthetic appreciation in relation to the thought of other German romantic theorists, discussing the central tenets of his musical aesthetic - the idea of a 'religion of art', of the composer as a 'genius', and the listener as a 'passive genius'. In particular the relationship between the multifaceted thought of Hoffmann and Friedrich Schleiermacher is explored, providing some insight into the way in which diverse intellectual traditions converged in early-nineteenth-century Germany. In the second half of the book, Hoffmann's dialectical view of music history and his conception of romantic opera are discussed in relation to his activities as a composer, with reference to his instrumental music and his two mature, large-scale operas, Aurora and Undine. The author also addresses broader issues pertaining to the ideological and historical significance of Hoffmann's musical and literary oeuvre.