The difference between our time and Gutenberg’s is, of course, the rate of change. It took almost half a century for the alphabetical index to become a standard; Arabic page numbers were not adopted until the 1500s. There were feature wars in the new platform of the book, but salvos were fired only every 20 years. It may have taken a long time, but when all those features coalesced into the system of citation, indices, page numbers, footnotes, bibliographies and cross-references that we now take for granted, they helped usher in the scientific revolutions of the modern age. Entire ways of interacting with information became possible because we had agreed on how to describe where the information lived and how to point people towards it.