[Harp-L] Chords and Modal Scales - Interrelationship(?)

[Robert Coble <robertpcoble@xxxxxxxx>]

As I was studying the diatonic chords based on the major scale (Ionian
mode), I was struck by something odd(?) regarding the thirds and fifths of
the chords that I have not seen discussed in music theory books.

(1) The notes used for the thirds of the chords form a Phrygian scale.

(2) The notes for the fifths of the chords form a Mixolydian scale.

For example, using the "C" major scale, here are the diatonic chords
(triads) based on the harmonization of chords using that "C" major scale:

G-A-B-C-D-E-F-G (Same as the Mixolydian modal scale)
E-F-G-A-B-C-D-E (Same as the Phrygian modal scale)
C-E-D-F-G-A-B-C (Same as the Ionian modal scale)
1-2-3-4-5-6-7-1 (Scale degrees of "C" major scale)

Having "discovered" something that has probably been around forever
(ignorance is NOT bliss for me), I continued to explore higher degree
chords. In actuality, the correspondence of modal scales to more complex
chords continues all the way up through all 7 modal scales. It is a
completely self-contained system!

Here is the actual use of all modal scales for building complex chords, all
the way up to the 15th (which is actually two octaves higher than the
starting note):

15-C-D-E-F-G-A-B-C (Same as the Ionian modal scale, two octaves higher)
13-A-B-C-D-E-F-G-A (Same as the Aeolian modal scale)
11-F-G-A-B-C-D-E-F (Same as the Lydian modal scale)
-9-D-E-F-G-A-B-C-D (Same as the Dorian modal scale)
-7-B-C-D-E-F-G-A-B (Same as the Locrian modal scale)
-5-G-A-B-C-D-E-F-G (Same as the Mixolydian modal scale)
-3-E-F-G-A-B-C-D-E (Same as the Phrygian modal scale)
-1-C-E-D-F-G-A-B-C (Same as the Ionian modal scale)
---1-2-3-4-5-6-7-1 (Scale degrees of "C" major scale)

(1) Does this information provide an interesting way to "cook up" some
harmony during solos, or is this unusable (useless) knowledge and merely an
oddity?

(2) Does anyone have suggestions for taking advantage (if possible) of this
interrelationship between diatonic chords and modal scales for practical
(NOT theoretical) purposes on harmonicas?

(3) Is this one of the (possibly many) reasons that harmonica experts
recommend learning ALL of the modal scales, as well as a host of other
scales (major and minor pentatonic, blues, whole-tone, harmonic minor,
melodic minor, jazz minor, etc.)?

Thanks!
Crazy ('bout harp!) Bob