First Piano Quartet was created in 1941.

The usual instrumentation in a piano quartet are:

* Piano * Violin * Viola * Cello

Gustav mahler plays the post horn, piano, etc.... He was a composer and a chef orchestrer. He is generally recognized as the last great German symphonist. He sought to expand the scope and breadth of the symphony to the greatest possible extent, believing that the symphony should "take in the whole world". The major influence on his work, however, was not a symphonic composer at all but rather that of Wagner, who was, according to Mahler, the only composer after Beethoven to truly have "development" in his music.

With the exceptions of an early piano quartet. Mahler's entire output consists of only two genres: symphony and song. His music is mostly in the tradition of astro-german.

the piano

Yes, the piano.