The poem starts with an overheard voice drifting across a river, a stranger's remark we only get secondhand. The speaker doesn't tell us who is talking or why. What we catch is a blunt idea: even the fittest person might be just as likely as anyone else to die "at the end of our lane." That last phrase pulls a big, abstract thought down to something very close and ordinary, a spot the speaker probably knows well.
Then the poem stops on a single image: "the moon." It isn't explained, which leaves it open. The moon might feel calm and indifferent, or quietly watchful, as if the thought of death has been placed under a wide, steady light. The speaker seems less alarmed than struck, simply listening and taking it in. The mood is hushed, a little eerie, and strangely peaceful. The short lines and spare words leave pauses, so the idea sinks in slowly, the way sound carries across water at night.