A couple of passing references have been made which I have to object to. First of all Carolan the composer was in every way concievable a trained and professional musician. He was not some idiot savant but a itinerant harper who played in what are the equivalent of today's concert hall. Secondly, the depiction of classical music as being something composed in stone rather than springing out of the available resources is at best, unprovable and at worst deceptive. No-one knows how Bach was first heard. We do know that most composers poached from folk tunes without any attempt to detail their sources. We do know that much of English choral music (e.g. William Byrd) was composed to be sung by servants in the houses of the English nobility. The pitch of any piece, the number of singers and the complexity of any given voice would be alterable to suit the voices available.
Let us not fall into the trap of believing: Naive=pure Composed=contrived Professional=mercenary Folk music seems to be a view through a telescope i.e. great for looking at things far away but increasingly useless the closer you attempt to focus.