Every day in New York City five million people ride the subways. Starting from their homes throughout the boroughs of Manhattan, Brooklyn, Queens, and the Bronx, they pour themselves in through hundreds of stations, pack themselves into thousands of cars that barrel though the dark labyrinth of the Metropolitan Transportation Authority’s tunnel system, and then once again flood the platforms and stairwells—a subterranean river of humanity urgently seeking the nearest exit and the open air beyond. As anyone who has ever participated in this daily ritual can attest, the New York subway system is something between a miracle and nightmare, a Rube Goldberg contraption of machines, concrete, and people that in spite of innumerable breakdowns, inexplicable delays, and indecipherable public announcements, more or less gets everyone where they’re going, but not without exacting a certain amount of wear and tear on their psyche. Rush hour in particular verges on a citywide mosh pit— of tired workers, frazzled mothers, and shouting, shoving teenagers, all scrabbling over finite increments of space, time, and oxygen. It’s not the kind of place you go in search of the milk of human kindness. It’s not the kind of place where you’d expect a perfectly healthy, physically able young man to walk up to you and ask you for your seat.