“When you see a book in the airport, you know what it is and what it’s for,” Mr. Suarez says. Ditto a book in an academic bookstore, although the cues will be rather different. “There are social codes kind of signaling to you all the time,” he says.
Those codes disappear, though, when a text escapes paper and becomes electronic. Put a bodice-ripper or a scholarly treatise on an e-reader and what remains is the text itself—what Mr. Suarez calls the linguistic codes of a book.