"The Listeners" describes a traveler who has come to knock on a moonlit door in an eerie, unknown place. He has come to keep an unnamed promise, and knocks on the door harder and harder, but gets no response. Unbeknownst to him, a "host of phantom listeners' (line 13) are inside but unresponsive to his calls. The traveler finally leaves, but the listeners remain.
The theme of the poem is the place of man in a universe which is far greater than he, and which he can neither connect with nor understand. It focuses on man's state of isolation and disharmony with the natural world. Nature, as represented by the horse placidly munching on the grass and the bird frightened by the man's disturbing clamor, is normally serene - it is only man who is anxious because of his separateness. The traveler tries to overcome his aloneness and establish meaning by fruitless seeking (knocking) and responsible living (keeping promises), but the natural world remains unyielding in keeping its distance, and the traveler continues on alone.