On the Dominant Ninth Chord: Wagner (3), Tristan und Isolde, part 1

Tristan und Isolde (1865), as is well known, is a treasure trove of chromatic harmonies and expressive appoggiaturas, accented neighbor notes, and simply non-harmonic notes of more than usual duration. My interest in it here, of course, is specifically with respect to dominant ninth chords, and this is a good moment to remind the reader that I am surveying only major dominant ninth chords in this series, not minor dominant ninth chords; that is to say, not this (a), but this (b). There are *many* minor dominant ninths, half-diminished seventh chords, and fully diminished seventh chords to be heard throughout this opera.

I have written the chords in the peculiar key of Gb in order to trace its viiø7 (or V9 without a root) to the "Tristan chord": spelled as in Gb at (c), then as at the opening of the Prelude at (d)—also see at (a) in the example below. Later on, at the climax point of the Prelude, the chord does appear spelled as F half-diminished7 and apparently acting as Eb: iiø7.

I certainly do not intend to add to the catalogue of solutions for the "Tristan chord" an enharmonically spelled C#9 chord with deleted root! The real point of interest lies elsewhere: first, in the dramatic tension between harmony and sonority in Wagner's insistence on the length of the G#4 appoggiatura and the brevity of its resolution note A4 (the only reasonable harmonic functional explanation for bar 2 is an augmented sixth chord that resolves to V7 in bar 3); second, in the continual shifting of roles between a pitch and its half-step neighbor. The initial ambiguity hints at this: is the long-held F4 a chord tone in bar 1 (part of a suppressed iv—which would make the progression a: iv-+6-V7), or is it an appoggiatura to E4 and thus the harmony in bar 1 is an incomplete tonic A3-(C4)-E4? By parallelism, bar 2 favors the second possibility, but observe that in bar 5 the long note is not heard as an appoggiatura but as a chord member of the preceding E7 (the same for B4 in bar 8: it is a member of the preceding G7 chord in bar 7). This shifting role for melodic elements is one of the hallmarks of Tristan und Isolde.

At (b) and (c) above, F#5 changes from the fifth of a B7 chord to the ninth in E9, which receives an internal ascending resolution, as sketched below:

By way of additional documentation, here are the subsequent few bars of the Prelude. The asterisks chart the profusion of non-harmonic notes of longer duration and traditional accented neighbor notes. The box shows the only possible V9 in this passage, and I think that V7 is more convincing here. But just as the first 17 bars suggested, the major dominant ninth chord is relatively rare -- that remains true for the opera as a whole: despite the dense textures of dissonant and complex harmonies, Wagner deploys the major dominant ninth for the same reasons and in the same places that we have seen many times by now in this blog: for an emotional surge in climaxes and near or in cadences.