Hi Tomo,
Please excuse me if you have already explained this and I missed it. I’m working on Lesson AT20 – Phrasing in Thirds.
I understand ascending in thirds: the notes follow the root and third of the ascending diatonic chords corresponding to the chord being played in the progression. For example:
• Over G: G – Am – Bm
• Over C: C – Dm – Em
When descending, however, I notice:
• Over C, the thirds are based on the diatonic chords for F (C-Bb-Am-Gm-F)
• Over D, the thirds are based on the diatonic chords for G (D-C-Bm-AM-G)
Is there a theoretical rule or principle that determines which key or chord the descending thirds reference?
Thank you for your help.
Brian