As for this turn around question, Even though there is an A7 instead of an Am7 in the progression, I'm not sure that it actually violates one of the rules. A7 certainly doesn't fit into the C Major on its own, but isn't it considered the V of the II chord? Somehow that's important. However, I'm really not sure how. I'm just learning a lot of this stuff. I think the progression works out to be:
iii, V/ii, ii , V
Em7, A7 , Dm7, G7
Somehow, the placement of the A7 between the Em7 and Dm7 makes the whole thing work, I guess because the Em7 and the Dm7 would be chords contained in both the C Major and D Major scales. Again, this stuff is still way over my head. I just like to think of the A7 as a color chord that "somehow magically" works in place of the Am7.
:cool:
