You see, the image of the book conjured up in our heads is the codex, a
stack of pages stitched together. But the codex is but one stage in the
grand evolution of books, and it has not always looked this way.
The same text, arranged in different physical media, gives rise to
different ways of reading.
-- Ken Liu. "The Grand Evolution of Books"
PowellsBooks.Blog Original Essays (March 10, 2016)
http://www.powells.com/post/original-essays/the-grand-evolution-of-books