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
Moses und Aron Moses und Aron Moses und Aron (English: "Moses and Aaron") is a three-act opera by Arnold Schoenberg with the third act unfinished. The German libretto is by the composer after the Book of Exodus. Hungarian composer Zoltán Kocsis completed the last act, with Schoenberg's heirs' permission, in 2010, but "Moses und Aron" was almost always performed as Schoenberg left it in 1932, with only two of the planned three acts completed. "Moses und Aron" has its roots in Schoenberg's earlier agitprop play, "Der biblische Weg" ("The Biblical Way", 1926–27), a response in dramatic form to the growing anti-Jewish movements in