Dear Mr. Prime Minister

They bamboozle us still. Marshall McLuhan started to write to Pierre Trudeau in April 1968, at the height of Trudeaumania. It was a unique period in electoral history: the new prime minister had become a hip sorcerer whose ability to seductively use the media seemed limitless. McLuhan was fascinated to see, right before his very eyes, someone who had instinctively hoodwinked the press and the broadcasters.

“Knowing of your acquaintance with De Tocqueville,” the professor mysteriously wrote in his first letter, “I can understand why you have such an easy understanding of the North American predicament in the new electronic age.” The rest was a mishmash of confusions and inaccuracies. When he received the note, Trudeau underlined a few phrases, including “French Canada never had a 19th century.” At the end, McLuhan observed that Trudeau had created an intimate connection to the “inner” life of the “TV generation.” Days later, McLuhan was even more exuberant, writing...