“When a rosy-faced tot tumbles off a seesaw, whacking his precious head on the playground turf, each subsequent moment is heavy with the threat of total apocalypse: his face will start to crumple, tiny pink mouth stretching open, eyes fluttering and nostrils rearing, sticky fingers clamping down on blades of grass. Onlookers will pause in thick silence, uneasy, leaning forward just a bit, waiting t”