" Reading off a page is like looking down at a landscape from a balloon – your eye " sees" the story as well as reads it, its layout, its paragraphs and structure, and " remembers" what it just read because it's still there, on the page, simultaneously. If you want to, you can reread any line instantly; or linger; or speed up; or optically " flinch." Reading a series of tweets is more like looking through a narrow window from a train speeding through a landscape full of tunnels and bands of light and dark. Each tweet erases its predecessor. "