I’m in New York City. An app on my phone shows me when anyone in my contact list comes nearby, and I see that my friend Mark Poirier is just a block away — I haven’t seen him in years, what a treat! So I go meet up with him. We’re hungry so we go to an underground food court to get doner kebab. But suddenly I realize, I’m not wearing a mask, nobody‘s wearing a mask, what am I doing inside in a crowded place unmasked? Fortunately I have one with me, so I put it on; but a woman in a block-print T-shirt first glares at me, then gets into it with me, insisting that I shouldn’t wear one. I don’t know how to respond; I feel chastened, even though I know I’m in the right.