I am not advocating the sheer accumulation of data, or arguing for links to databanks—so-called hyperlinks. These can amount to little more than an elaborate form of footnoting. Instead of bloating the electronic book, I think it possible to structure it in layers arranged like a pyramid. The top layer could be a concise account of the subject, available perhaps in paperback. The next layer could contain expanded versions of different aspects of the argument, not arranged sequentially as in a narrative, but rather as self-contained units that feed into the topmost story. The third layer could be composed of documentation, possibly of different kinds, each set off by interpretative essays. A fourth layer might be theoretical or historiographical, with selections from previous scholarship and discussions of them. A fifth layer could be pedagogic, consisting of suggestions for classroom discussion and a model syllabus. And a sixth layer could contain readers’ reports, exchanges between the author and the editor, and letters from readers, who could provide a growing corpus of commentary as the book made its way through different groups of readers.

A new book of this kind would elicit a new kind of reading. Some readers might be satisfied with a study of the upper narrative. Others might also want to read vertically, pursuing certain themes deeper and deeper into the supporting essays and documentation. Still others might navigate in unanticipated directions, seeking connections that suit their own interests or reworking the material into constructions of their own. In each case, the appropriate texts could be printed and bound according to the specifications of the reader. The computer screen would be used for sampling and searching, whereas concentrated, long-term reading would take place by means of the conventional printed book or downloaded text.

Robert Darnton, “The New Age of the Book” in The New York Review of Books, 18 March 1999.