Beethoven's epochal career is often divided into early, middle, and late periods, represented, respectively, by works based on Classic-period models, by revolutionary pieces that expanded the vocabulary of music, and by compositions written in a unique, highly personal musical language incorporating elements of contrapuntal and variation writing while approaching large-scale forms with complete freedom. Though certainly subject to debate, these divisions point to the immense depth and multifariousness of Beethoven's creative personality. Beethoven profoundly transformed every genre he touched, and the music of the nineteenth century seems to grow from his compositions as if from a chrysalis. A formidable pianist, he moved the piano sonata from the drawing room to the concert hall with such ambitious and virtuosic middle-period works as the "Waldstein" (No. 21) and "Appassionata" (No. 23) sonatas. His song cycle An die ferne Geliebte of 1816 set the pattern for similar cycles by all the Romantic song composers, from Schubert to Wolf. The Romantic tradition of descriptive or "program" music began with Beethoven's "Pastoral" Symphony No. 6. Even in the second half of the nineteenth century, Beethoven still directly inspired both conservatives (such as Brahms, who, like Beethoven, fundamentally stayed within the confines of Classical form) and radicals (such as Wagner, who viewed the Ninth Symphony as a harbinger of his own vision of a total art work, integrating vocal and instrumental music with the other arts). In many ways revolutionary, Beethoven's music remains universally appealing because of its characteristic humanism and dramatic power.