In this poem, the atmosphere of unearthly stillness is established from the beginning as the speaker describes "the moonlit door" upon which he knocks and "the silence" in which his horse is quietly chewing grasses. But the stillness is unearthly not because there is nothing alive in it, but because the Traveller feels anxiously that there must be—"a bird flew up out of the turret" in a sudden unexpected flurry of movement, which prompts the Traveller to knock a second time, the verb "smote" suggesting that this was a louder entreaty.
Whoever is in the house, though, the poet tells us, is not human—the "phantom listeners" thrive in the "quiet of the moonlight," their numbers evidently significant ("host," "thronging") and their motives unclear. We know that their presence is somehow detectible to the Traveller, who "felt in his heart their strangeness, their stillness," a comment which makes the reader feel very conscious of the Traveller's isolation amongst these unknown listeners. The poem is extremely enigmatic; who the listeners are, and what they are listening for, is never explained. Nor do we know why the Traveller has returned, his voice "echoing through the shadows of the still house," or what "word" he is keeping. But there is an undeniable eeriness in witnessing "the one man left awake" among these "phantom listeners," and in the mystery which is ultimately left completely to the reader's interpretation.