A friend and I were having coffee in Manhattan when the subject turned to life in Russia, where she used to live. Once in Moscow, she had slipped on a patch of black ice and fallen on her back, she remembered, and dozens of people walked past without so much as a glance. We agreed that the incident suggested something larger (and unflattering) about Russian society. Yesterday, as I was rushing to catch the G train, a distraught woman with a hospital bracelet, extremely swollen legs, and several open wounds, was sitting on a bench on the platform talking to herself. As I approached, she turned her attention to me. Her wheezy voice almost inaudible, she said she had skin cancer and did not have the strength to get to Union Square. I asked if she needed help and then went and told the station agent. When I came back to let her know paramedics were on their way, she continued to talk and plead for something—acknowledgment, sympathy, attention. Commuters streamed past, refusing to make eye contact. I edged away and scrutinized my iPhone. Before the train arrived, she stood up and walked toward the station exit, where the agent was posted. I breathed a sigh of relief, realizing she would now be in someone else’s hands—even as I knew, too, that I had done the least possible for her. I thought of those Russians who had ignored my friend as she lay on her back, and of these Brooklynites who had more or less done the same thing. And I thought of myself, and the degree to which this woman intruded into my mental tranquility. Finally, I wondered how much any of us really owe a stranger and how eager we are to shirk whatever little it may be.