-MY how cool the relations of the four chords a minor third apart are…

surely it’s just coincidence, somehow.

HOW LONG have composers made use of these?

Alan Silvestri and John Williams both did, (back to the future, star wars,) but fuck me, who else did?  and not just two major keys a minor 3rd apart, but three or four, preferable those such as

GM, BbM, DbM AND EM…

–