I bring all of this up because what my book is about is how our own tribe is undergoing a vast and trembling shift from the magic of writing to the magic of electronics. What I mean to point out here is that the introduction into a culture of a technique such as writing or a clock is not merely an extension of man’s power to bind time but a transformation of his way of thinking—and, of course, of the content of his culture. And that is what I mean to say by calling a medium a metaphor.