It switches on before anyone asks it to, sensing the dark the way older houses seem to sense weather, a small, private competence that goes unremarked for years. The hallway nightlight occupies the lowest socket in the corridor, six inches above the baseboard, where it casts a coin of amber onto the floorboards and nothing else. It does not illuminate; it merely refuses to let the hallway go entirely black. Children learn its exact wattage by heart, the way sailors learn a coastline: not by measurement but by repetition, the two a.m. walk to the bathroom conducted almost entirely by feel, the light serving only to confirm that the walk is still where it was left.
Specimens vary in housing, seashell, ladybug, unadorned plug, but the mechanism beneath is uniform: a photoresistor, a diode, a modesty so complete it has never once been photographed for its own sake. Guests do not compliment it. It is not meant to be seen, only to be present, a distinction the nightlight seems to understand better than most furniture. When it finally dies, weeks pass before anyone notices, and what they notice first is not the dark but a faint, specific loneliness in the hall at night, as though a small animal that lived there had quietly gone.