In the pretentious monochrome of Jim Harrison’s outmoded terminal, I see a flicker, almost a ripple. For a moment I think the dratted thing is finally failing, giving up to modernity, and halle-fucking-lujah. But no, it isn’t. Something is happening in the real world and it is reflected on the screen. The last digit of each stock value shifts to 4, just for a moment and one after another, running down the alphabetical list. For me this is like witnessing a solar eclipse or seeing Halley’s Comet, which I did when I was very small and plan to do again when I’m old. It is a rare and beautiful mathematical caprice called a Markov chain: an apparently meaningful sequence in a flow of random numbers. This is a particularly pretty one, a wonder of nature requiring a staggering string of coincidences. It looks almost like animation, conveys a sense of movement and of deliberation. The 4 moves back up the line, then hovers around the middle of the list.