In 1952 Eliot gave a lecture titled ‘Scylla and Charybdis’. It was not published until 1985¹ and may have been unknown to McLuhan.  But he was publishing on Eliot at the time and was part of a loose group of figures, including Eliot, Ezra Pound and Wyndham Lewis themselves, who were often longtime friends (Eliot, Pound and Lewis had known each other by then for over 40 years) and who were publishing poetry and essays on literary  and social matters in journals like The Sewanee Review and Shenandoah.  Eliot, Pound and Lewis all contributed to both these journals and McLuhan published more than a dozen essays and reviews in them in the 1940s and 50s. He was in correspondence with Pound and Lewis, while friends of his like Felix Giovanelli and Hugh Kenner were in touch with Eliot. Within this loose network much more was known about the activities of its various members than what found its way into print. So McLuhan may well have heard of Eliot’s lecture, if not seen it in samizdat.

However that may be, there are themes in the lecture which echoed Eliot’s past work and were of under active investigation by McLuhan at just that time.

The myth [of Scylla and Charybdis] belongs to that Mediterranean world from which our culture springs; it refers to a well-known episode in Mediterranean pre-history; like other myths in the story of Ulysses it is what I believe Professor Jung would call a universal archetype of human experience. It responds to some of the deepest desires, and terrors of all human beings: it is the experience of life itself. It is applicable to almost any subject one can discuss. (6)

The considerations I have been discussing are not, of course, equally applicable to every type of poetry, nor are they equally important in every poem of the same type. They are applicable to the degree in which philosophical ideas have contributed to forming the poet’s mind and have been digested into (we might say composted into) that profound couche of experience which constitutes the soil in which the germs of his poetry are nourished. They are peculiarly applicable when the matter of a poem, rich with philosophical ingredients, is organised into a structural design. (18)

Valéry’s poem has what I call the philosophic structure: an organisation, not merely of successive responses to the situation, but of further responses to his own responses. He has put more of himself into the poem — to that point at which the surrendering of the maximum of one’s being to the poem ends by arriving at the maximum of impersonality.  (19-20)

Eliot puts forward the view that the work of the individual poet is isomorphic with the work of western civilization (“that Mediterranean world from which our culture springs”) and even of “life itself”. All are founded in “that profound couche (…) which constitutes the soil in which the germs (…) are nourished”. It is the job of the poet (or at least of some poets) to reconnoiter the pathways to and from this seedbed and to formulate for us how it stands with it. 

Here is McLuhan in essays from this same time (some predating Eliot’s lecture):

1949
Mallarmé (…) saw that a poetry of effect was impersonal. The author effaced himself above all in not assigning causes or explanations as transitional devices of a novelistic and a pseudo-rationalistic type between the parts of the poem. Poetry could free itself at last from rhetoric and the novel. Insofar as a rationale of poetry was needed it is to be found naturally in the analogical drama of the very action of the intellect itself in making poetry. (Mr. Eliot’s Historical Decorum)

1951
the business of the artist in this context is that of an impersonal agent, humble before the laws of things, as well as before his own artistic activity as revealer. He must strip himself of all but his mere agency… (Joyce, Aquinas, and the Poetic Process)

1953
the artist, in order that he may perform his katharsis-purgative function, must mime all things. (…) He must become all things in order to reveal all. And to be all he must empty himself. Strictly within the bounds of classical decorum Joyce saw that, unlike the orator, the artist cannot properly speak with his own voice. The ultimate artist can have no style of his own but must be an “outlex” through which the multiple aspects of reality can utter themselves. That the artist should intrude his personal idiom between thing and reader is literally impertinence. (James Joyce: Trivial and Quadrivial)

1953
“Every letter is a godsend,” wrote Joyce. And, much more, every word is an avatar, a revelation, an epiphany. For every word is the product of a complex mental act with a complete learning process involved in it. In this respect words can be regarded not as signs but as existent things, alive with a physical and mental life which is both individual and collective. The conventional meanings of words can thus be used or disregarded by Joyce, who is concentrating on the submerged metaphysical drama which these meanings often tend to overlay. His puns in the Wake are a technique for revealing this submerged drama of language (…) For his view of the poet was that he should read, not forge, the signatures of things. As he explains in Stephen Hero, this involves the poet in a perpetual activity of retracing and reconstructing the ways of human apprehension.(James Joyce: Trivial and Quadrivial)

1954
it was Mallarmé who formulated the lessons of the press as a guide for the new impersonal poetry of suggestion and implication. He saw that the scale of modern reportage and of the mechanical multiplication of messages made personal rhetoric impossible. Now was the time for the artist to intervene in a new way and to manipulate the new media of communication by a precise and delicate adjustment of the relations of words, things, and events. His task had become not self-expression but the release of the life in things. (Joyce, Mallarmé and the Press)

1954
Mallarmé regarded the press as this ultimate encyclopedic book in its most rudimentary form. The almost superhuman range of awareness of the press now awaits only the full analogical sense of exact orchestration to perfect its present juxtaposition of items and themes. And this implies the complete self-effacement of the writer for “this book does not admit of any signature.” The job of the artist is not to sign but to read signatures. Existence must speak for itself. It is already richly and radiantly signed. The artist has merely to reveal, not to forge the signatures of existence. But he can only put these in order by discovering the orchestral analogies in things themselves. (…) All those pseudo-rationalisms, the forged links and fraudulent intelligibility which official literature has imposed on existence must be abandoned. And this initial step the press has already taken in its style of impersonal juxtaposition which conveys such riches to the writer. (…)  Mallarmé sees this impersonal art of juxtaposition as revolutionary (…) It is the rhyming and orchestrating of things themselves which releases the maximum intelligibility and attunes the ears of men once more to the music of the spheres. We are finished, he says, with that custom of an official literary decorum by which poets sang in chorus, obliterating with their personal forgeries the actual signatures of things. In fact, the new poet will take as much care to avoid a style that is not in things themselves as literary men have in the past sought to achieve and impose one.  (Joyce, Mallarmé and the Press)

In this view (which was far from being only McLuhan’s) humans are “amphibians” (as McLuhan cited Lewis from Snooty Baronet) who constantly move between the surface of life, language and consciousness and their motivating “germs” in an underlying seedbed. The great questions of the time, even in cybernetics, concerned this general picture and the ways in which it might be specified, investigated and communicated. McLuhan’s turn to media, which began to unfold at this time in the early 1950s, was his answer to these questions.