You responded to a question about tuning systems a while back. The asker wanted to know if you'd ever tried tuning completely in just intonation. You said it's a noble endeavor, but ultimately it's impossible; you couldn't even get a full major scale out of the harmonic series, much less a working system of chromatic harmony.  I've realized something which could go a long way towards solving this problem - I've even composed/arranged some nice music using this concept. (It is by no means my original idea, btw.)  Your problem was that you tried to create a major scale (C major, if I recall) in which each scale degree was only tuned one way, regardless of its 'function'. For example, F would always be the same pitch, whether it was the 3rd of a D minor chord or the 7th of a G7 chord.  The way I started thinking about just intonation tuning is this: all harmony diatonic to C major can be derived from the harmonic serie
 s of Bb 
 (minus 4ข, because C, in this case, is defined as the 9th harmonic of Bb).  In the C overtone series, we can get a very nice version of the C major triad (1st, 3rd, and 5th harmonics), the G major triad (3rd, 9th, and 15th harmonics), the E minor triad (3rd, 5th, and 15th harmonics), and the B diminished triad (15th, 9th, and 21st harmonics).  In order to get the three remaining triads, you need to use some 'undertones' of C - notes for which C is an overtone. I thought about it like this - if we get C major and E minor triads from the C harmonic series - we can just transpose down a (harmonic) perfect fifth to get F major and A minor triads. Then we can transpose down another perfect fifth to get the D minor triad (3rd, 5th, and 15th harmonics of Bb).  Since F-2ข and C are both overtones in the Bb-4ข harmonic series, and since each overtone has a harmonic series of its own (which is still part of the original harmonic series), we can say that a
 ll harmo
 ny diatonic to C major can come from the Bb-4ข overtone series and sound great.  However, to sound good, notes need to be tuned differently depending on what member they are in a chord. For example, the D minor triad in C sounds great on its own when tuned as the 3rd, 5th, and 15th harmonics of Bb-4ข. But the D minor triad can also be found within a G9 chord. In this case, a different tuning will be way more consonant - as the 3rd, 7th, and 9th harmonics of G+2ข (which is the 3rd harmonic of C and the 27th harmonic of Bb-4ข). If I remember correctly, this is how you tried to tune a D minor triad a while back - it sounds consonant in the context of a G9 chord, but not in the normal context of a D minor chord.  I realize this is not so practical for live keyboard or fretted instruments, but it's been great for retuning recorded music or composing in a DAW.  Thoughts?
it probably doesn't help that i've never seen this symbol before: ข, but essentially, what i discovered boils down to this, speaking in the key of C: the very nature of notes like D, F, G, and A, ... when all used together.... those all need to have certain relationships to each other simultaneously, which is actually impossible. the only way this 'secondary' chord seems to want to work is when it actually feels like all these relationships are true: the F and D have to have a good relationship, the F and A have to have a good relationship, the D and G have to have a good relationship, and the F and C, ... and the G and C, ...... and what i came to discover was that  it's actually this subtlely impossible nature that gives this chord such a longing need to go back 'home' to the 1 chord. kind of blew my mind. i explained all of this as well as i ever possibly could, right