Any theory of harmonic progression must contend in some way with the mutability of the sixth and seventh scale degrees in minor mode. The options of raised or lowered versions of these notes creates two-classes of diatonic chords. The first class consists of those chords that appear much more extensively than the others; their inclusion in any theory of harmonic progression is essential. The second class are those harmonies that appear least often; these chords fall below the line and are "downsized" out of the system. This study proposes a reexamination of one of those second class harmonies: the vi^ø7.

When other theories have considered the vi^ø7, they have described the chord as appearing in one or more of three possible contexts: 1) the vi^ø7 is created as part of a stepwise ascending melodic minor scale segment; 2) the vi^ø7 is created as part of a descending chromatic bass, or 3) the vi^ø7 is created as part of a common-tone harmony to the tonic triad. In the proposed study, I identify and explore another context in which vi^ø7 can aid in analysis. For chromatic music of later tonal practice that is less rigorously grounded in traditional harmonic relationships, vi^ø7 becomes useful as a shifting point between sections that rely on octatonic construction and those governed by more traditional functional harmony. These shifts typically involve cycles of harmonies that form intersections among the three octatonic systems and the twelve major-minor key systems. The involvement of these intersections shows that the vi^ø7 displays a unique property: its progenitor triad is included in a pair of octatonic systems distinct from those of ii° and vii°. different from the other diatonic chords of the same quality. Examples from the music of Wolf, Rimsky-Korsakov, and Harold Arlen demonstrates this application of the vi^ø7 and offers new evidence of its importance as a harmonic entity.