The names, dates of production, and principal singers of his music-dramas have already been given, together with some mention of his minor compositions. An overture (“Faust”), three marches, the “Siegfried Idyll,” built on themes from the drama, a chorus, a male quartet, a funeral march for Weber, five piano pieces, a few lovely songs (two of them studies for “Tristan” music), and nearly a dozen arrangements (among them piano scores of “La Favorita,” and “L’Elisir d’Amore,” pathetic mementoes of his starving days in Paris), are the musical remains of this genius, outside of his operatic works. The lyric stage was the theatre of his career, and in the works prepared for it he expended the force of his intellect, and developed the ideas that proclaim him an epoch-maker. Let us, therefore, turn our attention to the Wagner theories, and their practical exposition in the so-called “music of the future,” which has become so intensely that of the present. What is the Wagnerian theory of the opera? How does it differ from that which preceded it? From what germs did Wagner develop it? How has he embodied it? These are questions which naturally arise, and which demand answers. It may well be questioned whether Wagner had a wholly comprehensive view of the essence and results of his own artistic theories. There can be no doubt that much of his work was the fruit of what were in his own mind vaguer inspirations, which he himself was unable to reduce to theoretical formulæ. Therefore, while we may appeal to his prose writings for evidence as to the sincerity and direction of his intentions, we may readily agree with the assertion of Mr. Hadow that “the arguments which have established the Wagnerian theory of opera are to be found not in ‘Opera and Drama,’ but in the pages of ‘Tristan’ and ‘Parsifal.’”[8] It behooves us, therefore, to endeavor to trace the development of the Wagnerian theory in the mind of its inventor, and in order to do that we must follow the plan of Mr. Krehbiel,[9] and make some inquiry into “the origin and nature of the lyric drama.”