McLuhan was fairly sympathetic to Leary's project. For McLuhan saw the media as having become "extensions of man"—as much a part of us as our skin. To take control of one's media consumption was therefore a form of self-determination, a seizing of one's own destiny. And so after hearing Leary out, he finally gave him some counterintuitive advice: "You call yourself a philosopher, a reformer," said McLuhan. "But the key to your work is advertising." If Leary truly wanted to wean great numbers from the pernicious effects of the existing media, he needed first to reach those people by the media's most pernicious means. Most of all, he needed some kind of a catchy line, and to show him how it was done, McLuhan composed a jingle for him then and there, based on an old Pepsi ad: "Lysergic acid hits the spot / Forty billion neurons, that's a lot."

Tim Wu, The Attention Merchants, loc. 536