I resisted the urge to sneak a peek at the questionnaire of the man sitting beside me at jury duty a few weeks ago. He’d been totally unknown to me a half-hour before, but now, through the accident of being summoned to serve this civic duty on the same day, he was part of my world, an object of curiosity, my neighbor for the day. Who was this 30ish man in a plaid flannel who didn’t crack a smile when the hammy lawyer released a fellow juror with the quip, “Always the bridesmaid, never the bride”? Who were any of these people who, as I had, took the day off work and stepped out of the currents of their lives to enter this fluorescent-lit parallel universe of judgment and justice?

Jury duty presents an acute instance of the makeshift community: strangers who come together for a short period, and in that time become their own little society with its own customs and laws, its own characters and gossip. These accidental communities happen all around us, all the time: the people sitting around you on the beach, fellow passengers on a flight, other fans who started queuing for concert tickets before dawn. Unlike when, say, staying in the same bed-and-breakfast or sharing a cubicle at work, socializing is not expected; but just by being present, you’re part of the play.

How quickly people go from invisible to mattering! At jury duty, the woman who works at a nonprofit and grew up in Kansas has such thoughtful answers to the lawyers’ queries: She is the most beloved of all my new neighbors. We share a smile when we’re released for lunch, the pop-up community equivalent of best friendship. And that man in the cap watching a movie on his phone: He’s breaking the no-devices rule, and we all revile him.

By afternoon, we have familiarized ourselves with routes from the metal detector to the assembly room, assembly room to bathroom: These are our neighborhood’s streets. We all know the same sleepy security guard, the no-nonsense courthouse staff; they live here too. Our outside lives become dim — do we really have jobs and spouses and full-fledged personalities? Our friends have no idea about these people to whom we’ve uttered not a word but have somehow become our confederates, no inkling of all the infrastructure we’ve erected.

Then, as quickly as this society materialized, it evaporates. Those of us who have not been empaneled are abruptly dismissed at 4:30 p.m. There is no duty keeping us here, no actual ties to unravel, so we spill out the doors and stagger back to our actual friends and neighbors. We will probably not remember one another, and isn’t there a tiny bit of grief in that? How strange to periodically take up residency in these disposable towns, to participate in their bureaucracies so intensely and then never revisit them. We return home to our established relationships, the people we’ve lived beside for years, those who know us and whom we know. How wonderful to be recognized, depended upon, to contribute to the ongoing project of building a community we hope will last.