Many of Frost's poems convey a sense of loneliness, emptiness, alienation, and isolation. "Acquainted with the Night" is just such a poem. The speaker of this poem is walking out past the city lights on a rainy night. He hears nothing but the sound of his own feet, engulfed as he is by the silence of the darkness. When he passes the watchman, he lowers his eyes, and wehn he hears another human cry of suffering, he cannot acknowledge it. The night becomes a metaphor for the darkness and desolation of his spirit.
Another poem that conveys this same sense of isolation is "Desert Places." The snow falling on a field on a winter night is the setting for this poem. As the speaker watches the blankness caused by the blackness of the night and the whiteness of the snow, the speaker declares that
The loneliness includes me unawares.
In the second stanza, the speaker declares that
And lonely as it is that loneliness
Will be more lonely ere it will be less--
Just as in "Acquainted with the Night," nature becomes a metaphor for the speaker's internal state. At the end of this poem, the speaker admits that within him lie the most deserted of places--that this loneliness is not from without but from within.