Stephen McCauley writes: “I made a resolution to abandon my desk at home and only write in libraries. There’s something about each of these very different sanctuaries—with their noisy tourists, rambunctious schoolchildren, snoring visitors escaping the cold or heat, elderly jigsaw-puzzle aficionados—that allows me to leave behind the distractions of the world and my own self-doubts and believe that what I’m doing has some value.”