Hi, could someone please explain the theory behind using a major 7th chord on the flat sixth scale degree (for example AbMaj7 in the key of C)? You hear it every now and then in slick pop music (very Burt Bacharach-ish to my ears), a recent example for me is "Gravity" from John Mayer's last album. In the key of G the cadence is (roughly, inversions not being critical here): Am7 - D7 - EbMaj7 -D7. The major 7th chord leads very nicely back to the dominant, but my head is too tired to understand the logic and reason why... Sorry if this is a stupid question.