Writings by and about McLuhan trace his interest in the comparative study of media to his literary training at Cambridge in the 1930s which was occupied with the aesthetics of sight and sound and the predominance of representational forms over the content represented. This paper puzzles over the lack of reference -- by McLuhan, his mentors, and his critics -- to an earlier group of British thinkers (from Shaftesbury to Adam Smith) who deliberated over the differences among the arts. Their treatises on how the mind processes visual and auditory information remarkably foreshadow McLuhan's assertion that the media constrain how we think and feel. Present-day debate over the effects of new media technology, as well as current theories of reception, reflect McLuhan's stimulating (though exasperating) insights. His footprints also point to cognitive science and, of course, to globalism.