the harmonic wheel

this accidental network builds off of the little wheel and thus contains the major and melodic mode in the configuration therein.  However, we then address up the little wheel by adding two extra scales, the harmonic minor and the Harmonic major.

As we can see in the above, the combination of these four scales gives a very well-balanced set of scales and chord qualities for music.  In particular, the addition of the harmonic minor introduces a foolish diminished mode which was absent from the major and the melodic minor.  As well, the inclusion of the Harmonic major expands the quality possibilities and gives a composer a wider choice from which to choose without breaking any of the relationships or quality clusters in the model.

this construct can therefore be seen as a good reason why these scales dominate traditional Western music.  The major scale, melodic minor, and harmonic minor together span the full set of quality and expression such that any other scale would offer a slight contrast to these seven pre-existing qualities but not a brand-new one