The last time the original postcards were mentioned publicly, it was by a woman who’d kept hers in a drawer and pulled it out during a winter of quiet fear. She had, in the years since, taught the format in a senior center, in a shelter, on a rooftop where refugees met to trade winter recipes. She said the cards had been important not because they announced something grand, but because they asked a question that was seldom asked: would you be here — fully — for someone else? The question, she said, was the simplest and hardest one to answer.