The restaurant was lovely but dark. Only one small candle flickered on every table. To create light, diners used their smartphones to read their menus, look to their tablemates, and even to see what they were eating.

Finally, a patron quietly pushed back his chair, walked over to a waiter, and asked a simple question. “Could you turn on the lights?” Before long, a warm ceiling light flashed on and the room erupted with applause. But also with laughter. And happy chatter. And thank-yous. My friend’s husband turned off his phone, picked up his utensils, and spoke for us all. “Let…