Robert Frost's "Stopping by Woods on a Snowy Evening" appears, at first glance, to be deceptively simple in its meter and rhyme scheme. Upon closer inspection, however, we can see that something more complex and clever is happening, with rhyme being used cleverly as a thread to connect the four stanzas of the poem.
All the stanzas of the poem conform to the same meter. Of the stanzas, the first three have similar rhyme schemes: the first, second, and fourth lines all rhyme, while the third does not. This sound from the third line then follows through to the next verse, where it becomes the rhyme aaba, bbcb, ccdc.
This serves to highlight the word from the previous stanza which has now provided the focal sound for the stanza to follow. For example, "here" in the first stanza is isolated and has no rhyming pair; in the second stanza, it is echoed in the line endings "queer," "near," and "year."
The effect of this continuity of sound from one stanza to the next is, of course, most keenly felt in the final stanza of the poem. In the fourth stanza, all the lines rhyme (dddd). The sound suggested in the third stanza by the word "sweep" is continued through into the fourth stanza, where it rhymes with "deep," "keep," and then, twice, "sleep."
The change in rhyme scheme here has a cumulative effect, which could be said to represent the increasingly "deep" snow as it falls. The repetition of the word "sleep," too, in combination with the gentle sound of "sweep," is sonorous and somnolent, drawing the poem to a quiet and sleepy conclusion.