Just like good classical music or jazz can make you feel lonely or happy without any words, we bet that someone who had never heard English before would feel this poem's loneliness and darkness.
While the poem never uses the word "lonely," it uses the similarly sounding word "one" three times. The words "night," "light," "bye," "sky," "height," and "right," which are emphasized because they come at the ends of lines, all have long and piercing vowel sounds.
These sounds may be lonely and sad, but the poem has a beat, and is written in perfect iambic pentameter. This pattern of unstressed and stressed syllables is subtle, but, if you read it aloud, sounds like human footsteps – perhaps the footsteps of this speaker, trudging steadily through the loneliness of the night.
The rhymes in this poem swing back and forth, from stanza to stanza, just like a pendulum of a large clock would, or the moon's circular cycle.
In both the rhyme and structure of the poem, repetition plays a big part. The repetition of phrases like "walked out in rain – and back in rain" and the refrain of the line "I have been one acquainted with the night" helps emphasize the weariness and repetition of such dark and depressing nights.