A friend has helped me clarify a bit. (Like what happens when butter heats up and all the solids float to the top, I think.)
Regarding the post immediately previous to this one ...
It seems to me that:
"Art" is a subset of "Expression."
(Not all Expression is Art.)
"Communication" is a subset of "Art."
(Not all Art is Communicaton.)
Perhaps, then, Art is the intersection of Expression and Communication, when the subject at hand is the Unseen and the Un-embodied. (This would not be the same as disembodied.) In other words, when the Artist enters the Land Between, and brings back to the Corporeal Landscape something of that other land, he endeavors (or, I think he should endeavor) to communicate what he has seen (felt, heard, known). I just don't think it counts as Art if it's mere Expression alone. A tantrum is an expression, but it stops its communicating at the point where exasperation is the message. Eloquent, maybe. But not Art. Art is the embodying of that which has no body without expression. Isn't it?
Does ANY of this make sense outside my own head to ANYone else in the world? Comments please.