At almost the same time that McLuhan and his new wife were back in Cambridge to complete his PhD requirements in 1939-1940, Ludwig Wittgenstein has been described by C.H. Waddington considering language and language learning there as follows:

During one summer, 1940, I think, or 1941, Wittgenstein and R. H.Thouless and I used to meet one evening every week, and spend three or four hours after dinner discussing philosophy in the Roundabout Garden of Trinity, Cambridge. The subject of most of these discourses was the relationship between a word and the thing it signifies. I vividly remember those twilit evenings, when Wittgenstein would jump up from the lawn on which we had been sitting and pull out of a pocket of his shabby sports coat a matchbox or some other small object. As he held it up in front of us and tried to make us realize the impervious vacuity of the gap which exists between the object in his fingers and the auditory modulation of air pressure or the black marks on white paper by which we refer to it, his main weapon of exposition was to persuade us to shed the preoccupations of the first year of the Second World War and to feel ourselves again children whose mother was instructing us in our first words. Something of the same method — a method which explicitly recognizes the importance of a developmental analysis of language¹ — comes over in the first four pages or so of the Philosophical Investigations, but it was of course incomparably more vivid when the phrases were formulated slowly and painfully by Wittgenstein himself, his face (…) frowning and contorted with the effort to express precisely his understanding of the way in which the relation he was discussing is inexpressible. Often, indeed, his words came to a standstill…²