What we symbolize in black the Chinaman may symbolize in yellow; each has his own tradition. Greek beauty laughs at Coptic beauty and the American Indian derides them both. It is almost impossible to reconcile all tradition whereas it is by no means impossible to find the justification of every form of beauty which has been adored on the earth by an examination into the mechanism of esthetic apprehension whether it be dressed in red, white, yellow or black. We have no reason for thinking that the Chinaman has a different system of digestion from that which we have though our diets are quite dissimilar. The apprehensive faculty must be scrutinized in action. (James Joyce, Stephen Hero, as cited in CHML¹)

It was the Thomistic awareness of analogy derived from sense perception that gave Joyce the means of digesting all the ideas of all his contemporaries without relying on any of them as a (…) frame of reference. (CHML)

What [Etienne Gilson] does is to elicit the image of truth from past errors [“All those pseudo-rationalisms, forged links and fraudulent intelligibilities which official literature has imposed on existence”]² and to confirm the unity of man’s quest from the jarring discords of unremitting debate. But what I wish to point out is that Gilson’s method is that of contemporary art and science (for contemporary poetry has healed the old breach between art and science). Gilson does not set out to produce a theory or view that will unify the philosophical disputes of the past. (…) We don’t arrive at a simple unifying concept but are put on the road to achieving a wisdom. And the road to this wisdom is by way of sympathetic reconstruction, involving the abeyance of personal prejudice and preconception. (CHML)

By 1954, almost all of the pieces of McLuhan’s mature position were in place. He could sense that a theory of theories was possible which would cover “the entire world of language and consciousness”³: “all the ideas of all“.  It would function not as one more perspective in “the jarring discords of unremitting debate” among perspectives, but exactly through “the abeyance of personal (…) preconception” — ie, “without relying on any [one perspective] as a prop or frame of reference“.  This it would accomplish, in turn, through focus on “the mechanism of esthetic apprehension“, of “the apprehensive faculty (…) in action“, across every possible perspective, “by way of sympathetic reconstruction“.

In another 1954 article, ‘Sight, Sound and Fury’ (Commonweal, April 9, 1954) McLuhan put these points as follows:

What we have to defend today are not the values developed in any particular culture or by any one mode of communication. Modem technology presumes to attempt a total transformation of man and his environment. This calls in turn for an inspection and defense of all human values. And so far as merely human aid goes, the citadel of this defense must be located in analytical awareness of the nature of the creative process involved in human cognition.

“Sympathetic reconstruction” of “all the ideas of all“, aka of “human cognition” in general, would function, furthermore, just as “contemporary art and science” already function — “for contemporary poetry has healed the old breach between art and science“. It would analyze any sample of experience in terms of the process through which it had come to be synchronically. So chemistry analyzes materials not in terms of how they happened to evolve in historical or diachronic time (iron rusting in water), but in terms of their necessary development according to synchronic law (Fe + O => Fe₂O₃). Similarly, modern art or poetry is not interested in how certain images came to be associated historically, but in their synchronic relationship in “the universal fabric” (The Mechanical Bride, 3).

Hence McLuhan’s observation in CHML that “the poetic process is a reversal, a retracing of the stages of human cognition”. This is no “retracing of (…) stages” in backwards linear time, but exposure by such images of their underlying synchronic prerequisites exactly as images of “cognition” or “apprehension” — something like Fe + O => Fe₂O₃, but where chemical law concerning chemical elements is replaced by “human cognition” law concerning the elements of “esthetic apprehension“. 

Now in 1954 McLuhan had a rough idea of such cognitive elements.  From a variety of sources (Wright, Lodge, Gilson, Muller-Thym, Richards, Giedion, Havelock, Innis) he understood human experience as pre-shaped by underlying types (realist, idealist, pragmatist) or disciplines (rhetoric, logic, grammar) or media (speech, print, electronics) or sense (ear, eye, touch) or different flavors of spaces and times. And he had a rough idea of the inter-convertibility of these classifications.⁴

But what he did not yet have was exactly what had provided Einstein with his key to the formulation of relativity: co-variance.  This McLuhan would come to see at some point between 1955 and 1960 through his exposure to, and subsequent reflection on, “acoustic space“. The essence of the matter is that law can depend either on a fixed frame of reference or on some dynamic co-variability that functions across all frames of reference.  For both Einstein and McLuhan a fixed frame of reference (Newtonian physics for the one, the Gutenberg galaxy for the other) was exactly the problem that had to be overcome. Their solution therefore depended on finding a formulation of co-variance that could be used in place of any fixed framework.

For McLuhan this meant that he had to find a way to specify the elements of “the mechanism of esthetic apprehension” in terms of a co-variability,  But which elements according to what co–variability would have to fall in place together, since only the co–variability would expose the elements and only the elements the co–variability.