:D Ahh. Chris man, you know that's not what I meant and you know what I mean.. LOL ;) I wasn't talking about chords with extensions. I'm talking about the chordal structure of a key signature, the foundation that makes up the sub-dominant, mediants and stuff like that. And no chord in that foundation is an extension of another chord. Start adding extenions and yes what your saying is true.

ALthough I understand it, I am not all that favorable with the whole chord within a chord idea. A Cmaj9 sounds like a Cmaj9 chord, regardless of the chord(s) inside. Chord Substitution is the same way, the chord still sounds like the chord it is rather than the chord it is substituting. A C13 chord can carry inside it, any chord that exists within a C major scale. But it doesn't sound like any chord other than the C13 chord. A study for the intelligent theorist but not for the aural musician. Maybe a shortcut for the pianist though.

Man theory is a bust, for every point made there is an equal counterpoint.