In his "Confessions," which dates from the end of the fourth century, St. Augustine famously hears a voice telling him to "pick up and read." He interprets this as a command from God to pick up the Bible, open it at random and read the first passage he sees. He does so, the scales fall from his eyes and he becomes a Christian. Then he bookmarks the page. You could never do that with a scroll.
But so far the great e-book debate has barely touched on the most important feature that the codex introduced: the nonlinear reading that so impressed St. Augustine. If the fable of the scroll and codex has a moral, this is it. We usually associate digital technology with nonlinearity, the forking paths that Web surfers beat through the Internet's underbrush as they click from link to link. But e-books and nonlinearity don't turn out to be very compatible. Trying to jump from place to place in a long document like a novel is painfully awkward on an e-reader, like trying to play the piano with numb fingers. You either creep through the book incrementally, page by page, or leap wildly from point to point and search term to search term. It's no wonder that the rise of e-reading has revived two words for classical-era reading technologies: scroll and tablet. That's the kind of reading you do in an e-book.