Well, you get the idea. In any case, my feeling is that the melody and bass create harmonic functions that become increasingly blurred by the ever-growing inner-voice cluster. Specifically, I think it's possible to hear the following functions in bars 1-5, especially since the melody and bass outline these chords so nicely: A minor: i - III6 - VI After that, it starts to get rather murky, bar 6 perhaps suggesting minor v, but after that getting even more difficult to tease out any functions (perhaps viio6 - I in C major suggest themselves). By the end of the buildup, I would say it sounds entirely like a cluster with no suggestion of function. So one could say the passage moves from clear functional harmony to non-functional harmony. Just a thought. Thanks for your input, I definitely see how one could hear the proposed progression if you focus strictly on the two contrapuntal lines and disregard the inner voices as a type of harmonic wallpaper that simply colors the overarching tonal progression. Certainly if you remove all the sustained voices in the middle of the texture, you are left with a simple harmonic skeleton that suggests your diatonic progression (although I believe you meant III6/4 instead of III6). And you're right that this could be be considered pandiatonicism, although the passage is constructed in such a particular way and in such an isolated manner (surrounded by what are clearly diatonic materials) that I avoided the use of such a term. Certainly we could consider this very particular additive process as a pandiatonic technique since it sticks to the 7 diatonic tones rather than the 12 chromatic tones, such as in the Scriabin. Great insights, it's always refreshing to hear alternative viewpoints of the same theoretical concept! Also, I loved how you succinctly termed this technique as "clustural accretion." I'm going to add that bit of terminology to my repertoire.