This book by John Hollander, who was also a well-regarded poet back in the day, was one I read and then didn't look at for several decades. It was a dissertation at the U of Indiana. The thesis of the book is this:
"From the canonical Medieval Christian view that all actual human music bears a definite relation to the eternal, abstract (and inaudible) 'music' of universal order, to the completely de-Christianized, use of such notions in late seventeenth-century as decorative metaphor and mere turns of wit, a gradual process of disconnection between abstract musical terminology and concrete practical considerations of actual vocal and instrumental music occurs." (19).
Note the richness and specificity of the thesis. This is something that needs a book to document, not the kind of thesis one would expect in a 6,000 word article. The historical scope is broad, and requires knowledge of intellectual history, British poetry of the periods involved, and music, both in its actual forms and in what Hollander calls the "musical thought" or "ideology."
I recommend, too, another book by JH on The Figure of Echo.
I had remembered this idea in vague terms. What interests me here specifically is the transition from musicality as a profound trope to a weaker one, described as "decorative metaphor and mere turns of wit." Yet with romanticism and symbolism music becomes, again, a deep metaphor, not a decorative one. A retuning of the skies, but without the medieval belief in the literal "music of the spheres"?