I think of the two modes we know best: Ionian and Aeolian, and realize that they are 'modes' and that chords that we call 'diatonic' (which I understand as 'containing the natural notes of the scale from which they are built' ...or something to that effect), are predictable and consonant sounding to our 'tertially-geared' ears.

Modes, as a means to extend or alter chords, (as you pointed out), gives us a strategy to play other relevant scales over a given chord or piece of music and break out of the diatonic box of a one given key. Perhaps this is a different thing all together, but the notes are still derived from one of the major scales.

I understand your statement of modes being entities in their own right, but the bottom line is what colours we get (and what colours we want).

So, my question is: if we build our chords in quartal harmony, do we get new modes or a new diatonic structure, or both?

SarinaJ :confused: