"Written Near a Port on a Dark Evening" begins with the speaker describing the vapors and fog over the ocean, saying that the night is quiet and dark. However, she then goes on to list several ambient sounds. One of these sounds is the roar of the ocean's relentless waves hitting rocks on the shoreline. Then there are sailors, whose voices can be heard calling as they change shifts. Finally, the speaker hears a single voice announcing the time and asking someone to strike a bell for the hour.
Meanwhile, the speaker says, the only thing visible in the darkness is the line where the sea and the sand meet. But, in the distance, something else is also visible: the lights of passing ships. They look like "fairy fires," lights (according to folklore) held by fairies to lead confused travelers astray.
Reminded of these fairy fires, the speaker notes that the misleading lights are similar to reason. Reason, she says, offers a misleading "light," baselessly promising certainty during a long and uncertain life.
