https://www.amazon.com/Classical-Trivium-Place-Thomas-Learning/dp/1584232358

McLuhan outlines how Grammar & Rhetoric were inseparable in the development of the Patristic method of interpreting Scripture (and the book of the world), and how certain controversies arose with those who sought approach the logos through Dialectic means. Later in his life, McLuhan sought to rewrite this thesis with a newly-gained understanding of the gnostic values embedded in the approach that subjugates the grammar to logic. Nonetheless, it’s an excellent source for exploring how the controversies within language developed over time throughout Western civilization, beginning with the Ancient Greeks and winding up in Queen Elizabeth I’s England.

Your closing quote from T. S. Eliot is also quite interesting, as Marshall wrote an essay about “T. S. Eliot & The Manichean Myth as Poetry”, where he goes in-depth on the topic of gnosticism.

“Grace in Mr. Eliot’s work (his private life, of course, is quite another matter) is self-generated.”

https://www.thefreelibrary.com/Eliot+and+the+Manichean+myth+as+poetry.-a0280004567

All the best,
Peter