From movable type to movable text

The Review section of tomorrow's Wall Street Journal includes a brief essay by me on what I think will prove to be one of the most radical consequences of the rise of electronic books: the ability to perpetually revise a book even after it's been published. We take for granted the fixity of text in a printed book. But on a Net-connected digital reader, fixity disappears, replaced by endless malleability. Here's how the piece begins: I recently got a glimpse into the future of books. A few months ago, I dug out a handful of old essays I'd written about innovation, combined them into a single document, and uploaded the file to Amazon's Kindle Direct Publishing service. Two days later, my little e-book was on sale at Amazon's site. The whole process couldn't have been simpler. Then I got the urge to tweak a couple of sentences in one of the essays. I made the edits on my computer and sent the revised file back to Amazon. The company quickly swapped out the old version for the new one. I felt a little guilty about changing a book after it had been published, knowing that different readers would see different...