Max Kalbeck was a close friend and partisan of Johannes Brahms. Kalbeck's principal achievement was his eight-volume biography of that composer, published from 1904 to 1914, which has never been translated into English. Kalbeck also edited several volumes of Brahms's correspondence and in 1918, the letters of the poets Gottfried Keller and Paul Heyse, as well as publishing two collections of his own music reviews. Kalbeck wrote new libretti for Mozart's "Bastien und Bastienne" and "La finta giardiniera"; and he revised those of "Don Giovanni" and "The Marriage of Figaro" for Gustav Mahler's productions at the Vienna Hofoper. In addition, he supplied
Vienna State Opera of the Staatsoper. Recent examples include "Peter Pan", "" ("The Dream Gobbler"), "Der 35. Mai" ("The 35th of May"), C. F. E. Horneman's "Aladdin", "Bastien und Bastienne" and "Wagners Nibelungenring für Kinder" ("Wagner's Ring for children"). In addition to this, there is a production of "The Magic Flute" every year for 9- and 10-year-olds, decorated like the Opernball. The opera house also has an opera school for boys and girls between the ages of eight and fourteen, which takes place in the afternoons after regular school. The children are introduced to music theatre and the prospect of becoming opera singers.