"At forty Strauss is the most commanding figure in the musical world of to-day. It will be an interesting disclosure for future years to make as to how much of his lifework he has already accomplished, and whether the salient characteristics are already fixed and contained in what he has done, or whether this is but a preparation. We may be reminded that on their fortieth birthdays Mozart and Schubert had put the final seal upon their work, Mozart five years before, Schubert nine. Beethoven had given to the world his first six symphonies, his 'Fidelio,' and the 'Leonore' overtures, the 'Coriolanus' overture, the 'Egmont' music, the five piano concertos and the violin concerto, nine string quartets, including those dedicated to Count Rasoumoffsky; the 'Kreutzer' and the earlier violin sonatas, the 'Waldstein' and the earlier piano sonatas. Wagner had written 'Rienzi,' 'The Flying Dutchman,' 'Tannhäuser,' 'Lohengrin,' 'Eine Faust Ouvertüre,' and had conceived and partly executed 'The Ring of the Nibelung.' And yet these two had not given the finest fruitage of their genius. What Strauss has done in his younger manhood will not, perhaps, be counted of greater worth. Whether, like these two at his age, he will go on to further development may also be curiously questioned, and whether he will turn aside from the path in which he has already started. On that path he seems already to have reached the furthest confines of the territory he has traversed." X. (=Classification of Compositions.=) Similar to the works of most composers who have a genuinely original message to give to the world, those of Strauss may be divided into distinct groups of differentiated creative periods. He has progressed step by step through various stages of development. Conforming at first to the conservative romanticism founded upon traditional forms of Mendelssohn and Schumann, he soon came to admire and emulate the doctrines of Brahms--an influence that has never been effaced from his subsequent writings even though his associations with von Bülow and Ritter caused him to lean more and more upon Wagner and Liszt for the dominating thought of his conceptions. With one stroke, however, "Macbeth" and "Don Juan" went far beyond the tenets of the Weimar coterie, though the succeeding productions "Tod und Verklärung" and "Guntram" suggest what has been called a _reaction_ toward Liszt and Wagner. But with "Till Eulenspiegel" and "Also sprach Zarathustra" Strauss inaugurated a permanent and ever advancing method of procedure distinctively individualistic and unprecedented, that has so far culminated in the vast realistic tableaux of "Don Quixote" and "Ein Heldenleben."