In 1974, McLuhan looked back 40 years in ‘English Literature as Control Tower in Communication Study’:

lt was a little book by F. R. Leavis and D. Thompson called Culture and Environment (London: Chatto and Windus, 1933) that first directed my attention to the role of advertising and movies in shaping the awareness of students in general.
l began teaching at the University of Wisconsin in 1936, having come from Cambridge, where language and popular culture as forms of perception and perceptual training were a somewhat new and exciting development. After all, it was the radio age, and sound movies were well established. A holistic attitude toward the planet as a single human environment had become natural and acceptable. Radio had created a simultaneous world of information, which in effect, bypassed all the existing divisions of knowledge with their schematic and visual classifications. Physics and astrophysics and anthropology alike were asserting the new claims of the inclusive and resonating world of quantum mechanics on one hand, and the “Third World,” on the other. For the Third World arrived with radio and anthropology and with the study of preliterate or “traditional” societies.