The string quartet often served as a kind of guinea pig for composers' experimentation and innovation, especially in the Classical period, and the peculiar bright, sometimes astringent (generally in a good way) sound of this arrangement of instruments foreshadows that of 20th Century Music. (Scientifically, this sound partly owes the violin's unique quality that its first harmonic can be louder than the fundamental, though this depends a great deal on personal style). A good example is perhaps Mozart's String Quartet no. 19 in C major K465, dubbed 'Dissonance,' which many balked at when first played. Mozart and Haydn, and later also Benjamin Britten, were keen violists, and they sometimes played the alto part in their own and their friends' works, entrusting the first violin to a professional musician while retaining some control over the piece's early performances. Perhaps if Schoenberg could have participated in the first performances of his atonal music it would have had more early success.