Glad its bumped. Finished your post prod S? I've been patiently waiting.
I notice the old question has arisen in astro forum again ... but I wont be discussing things there again!
Anyway, this decan thing... it seems to me that stars were used in early astrology. A star had an influence, or perhaps I should say; a deamon had an influence and deamons related to many things, including stars.
Anyway, as was pointed out in the astro forum some time ago (to discredit my ideas?) 'signs' were considered to be like orange segments and included all that space up to the north pole (they said both poles but I doubt back then there was much knowledge of the south pole), ie. a 'sign' did not include just the band of the ecliptic (note; band - not path) but all space enclosed within that segment. That is why in old charts a particular star may be given as X degrees Cancer (for example) but that star may be several constellations 'above' the constellation of Cancer.
For me this gives the idea (outlined in above posts) that the signs themselves (as conglomerations of the decans) were given a certain influence which is a multiple of the 3 decans making it up, yet the decans themselves seem to to be doing the same, that is, it isnt the decan that has an influence but a star in that segment, even though the star may not be anywhere near the ecliptic, even up near the pole. If one draws a line from the star to the ecliptic (so it crosses the ecliptic at 90 deg.) that stars infleunce will be combined with any planets or planetary aspect in relation to the point that the lines cross.
IMO it all came about by the influence of stars (as I stated orignally sooooooo long ago that astrology was SUPPOSED to be about the study of stars moving and FIXED).
So then, it isnt so much that Virgo influences us because that aspect of the sky has an infleunce, nor that a specific decan of Virgo influences us, again, because that smaller part of the sky influences us (the decan). But if planetary aspects relate to, say, Spica, then that would have been seen as the influence.
But then again I have been called all sorts of names by astrologers be even suggesting that fixed stars have an influence.
Oh - hum!
I'd really like to get my hands on some more Ficino - he had it down I reckon.