Editing Tristan und Isolde (section)

==Significance in the development of Western music==
The score of ''Tristan und Isolde'' has often been cited as a landmark in the development of Western music.<ref>Rose, John Luke. "A Landmark in Musical History" in {{harvnb|Wagner|1981|p=15}}.</ref> Throughout the opera, Wagner uses a remarkable range of orchestral colour, harmony, and polyphony, doing so with a freedom rarely found in his earlier operas. The first chord in the piece, the ''[[Tristan chord]]'', is of great significance in the move away from traditional tonal [[harmony]] as it resolves to another [[Consonance and dissonance|dissonant]] chord:{{sfn|Magee|2001|p=208}}

<score lang="lilypond" override_ogg="Wagner Tristan opening (orchestral).ogg">
    {
      \new PianoStaff <<
        \new Staff <<
            \new Voice \relative c'' {
                \clef treble \key a \minor \time 6/8
                \voiceOne \partial8 b8\rest R2. \once \override NoteHead.color = #red gis4.->(~ gis4 a8 ais8-> b4~ b8) \oneVoice r r
                }
            \new Voice \relative c' {
                \override DynamicLineSpanner.staff-padding = #4.5
                \once \override DynamicText.X-offset = #-5
                \voiceTwo \partial8 a\pp( f'4.~\< f4 e8 \once \override NoteHead.color = #red dis2.)(\> d!4.)~\p d8
                }
            >>
        \new Staff <<
            \relative c {
                \clef bass \key a \minor \time 6/8
                \partial8 r8 R2. \once \override NoteHead.color = #red <f b>2.( <e gis>4.)~ <e gis>8 r r
                }
            >>
    >> }
</score>
The opera is noted for its numerous expansions of harmonic practice; for instance, one significant innovation is the frequent use of two consecutive chords containing tritones (diminished fifth or augmented fourth), neither of which is a diminished seventh chord (F–B, bar 2; E–A{{music|sharp}}, bar 3). ''Tristan und Isolde'' is also notable for its use of [[harmonic suspension]] – a device used by a composer to create musical tension by exposing the listener to a series of prolonged unfinished [[cadence]]s, thereby inspiring a desire and expectation on the part of the listener for musical resolution.{{sfn|Magee|1983|p=356}} While suspension is a common compositional device (in use since before the Renaissance), Wagner was one of the first composers to employ harmonic suspension over the course of an entire work. The cadences first introduced in the prelude are not resolved until the finale of act 3, and, on a number of occasions throughout the opera, Wagner primes the audience for a musical climax with a series of chords building in tension – only to deliberately defer the anticipated resolution. One particular example of this technique occurs at the end of the love duet in act 2 ("Wie sie fassen, wie sie lassen...") where Tristan and Isolde gradually build up to a musical climax, only to have the expected resolution destroyed by the dissonant interruption of Kurwenal ("Rette Dich, Tristan!"). Resolution of the music does not occur until the very end of the opera, after Isolde sings the closing excerpt commonly referred to as the "[[Liebestod]]" ("Love-Death"), after which she sinks down, "as if transfigured", dead onto Tristan's body.{{sfn|Millington|1992|p=252}}

The tonality of ''Tristan'' was to prove immensely influential in western Classical music. Wagner's use of musical colour also influenced the development of [[film music]]. [[Bernard Herrmann]]'s score for [[Alfred Hitchcock]]'s classic, ''[[Vertigo (film)|Vertigo]]'', is heavily reminiscent of the "Liebestod", most evidently in the resurrection scene. The "Liebestod" was incorporated in [[Luis Buñuel]]'s [[surrealist]] film ''[[L'Age d'Or]]''. Not all composers, however, reacted favourably: [[Claude Debussy]]'s piano piece "[[Children's Corner|Golliwog's Cakewalk]]" mockingly quotes the opening of the opera in a distorted form, instructing the passage to be played '{{lang|fr|avec une grande emotion}}'. However, Debussy was highly influenced by Wagner and was particularly fond of ''Tristan''. Frequent moments of ''Tristan''-inspired tonality mark Debussy's early compositions.