Wagner - Tristan und Isolde

     Tristan und Isolde, WWV 90  (1857 - 1859)

            Widely acknowledged as one of the peaks of the operatic repertoire, Tristan
      was notable for Wagner's unprecedented use of chromaticism, tonal ambiguity, 
      orchestral color and harmonic suspension.

            The opera was enormously influential among Western classical composers and 
      provided direct inspiration to composers such as Gustav Mahler, Richard Strauss, 
      Karol Szymanowski, Alban Berg, Arnold Schoenberg and Benjamin Britten.  Other 
      composers like Claude Debussy, Maurice Ravel and Igor Stravinsky formulated their 
      styles in contrast to Wagner's musical legacy.  Many see Tristan as the beginning of the 
      move away from common practice harmony and tonality and consider that it lays the 
      groundwork for the direction of classical music in the 20th century.  Both Wagner's 
      libretto style and music were also profoundly influential on the symbolist poets of the 
      late 19th century and early 20th century.