Wagner (4), Siegfried Idyll

Wagner's Siegfried Idyll was composed in 1870; a private premiere took place that year, the public premiere in 1876, and the piece was published in 1878. About the use of the major dominant ninth chord, I have little that's new to say. The examples below show two distinct uses, literally soft and loud in cadences or climax points.

Near the beginning, arrival on V, then two treatments of V9, as V9 at (a), and as V9/V at (b).

Shortly thereafter, another "soft" moment: the sudden drop in dynamics and slowing of movement and harmony:

The remaining examples are all the typical treatment of V9 in climaxes.  At (d), the chord is in an approach to a cadence, which turns out to be deceptive.

At (e), V9/V in Ab major, resolved internally in its second bar.

At (f), C: viiø7/V--an "incomplete dominant ninth chord" that leads to a pedal dominant.

At (g) a very similar use of the "incomplete" chord; here C: viiø7 alternates with iiø7. At (h), a complete dominant ninth chord, as C: V9/V. It drifts off chromatically towards E major instead; I have sketched the voiceleading below the score.