Major keys...

[HelenaZF]

The first thing that came to mind reading the above was a church edict of sorts made about never ending a song with a minor chord, but always a major one.



It came from the fact that in the acoustics of cavernous old cathedrals, the way sounds bounced off the walls would take the harmonics of a minor chord and transform it into the aurally disturbing mess of having both the actual minor third sounding and the sympathetic major third sounding (because of some complex physics laws about intersecting harmonics) therefore, the Picardy 3rd was birthed in musical practice. The harmonics of a major chord remained true in the acoustical bouncing, and was therefore deemed the preferred ending.



(a bunny trail, but I think interesting...)

The one problem with the so-called "major" keys is the regular appearance of the diminished 5th (same notes as the augmented 4th), known as the sinister "diabolicus musicus". This was a problem in early music, when parallel 4ths & 5ths were the norm. The sound rankled everyone; it was to be avoided at all costs. Problem was that it's an interval that begs resolution to either a third or a sixth. They did not do those, so it was to be avoided.