In almost all of her poems, Emily Brontë employed an ABAB rhyme scheme. While on the surface this might appear to be a fairly standard formal feature of her era, it actually serves an important, distinctive purpose in her work. The rhyme functions as an organizing principle for her stanzas, usually quatrains, putting the lines together in such a way that makes it clear that they are one coherent statement. Making the rhyme occur across four lines marks those lines more clearly as a single unit of verse. There are numerous examples of this throughout Brontë's body of work.
In the opening of "The night is darkening round me," the reader sees the effect of this structuring:
The night is darkening round me,
The wild winds coldly blow;
But a tyrant spell has bound me,
And I cannot, cannot go.
Here, the rhyme scheme allows Brontë to place two images in the first half of the stanza ("darkening sky," "wild winds"), before explaining their significance in the second ("tyrant spell"). The speaker finds herself unable to leave a spot in the woods as evening falls. The rhyme is important here in that it connects the natural imagery with the explanatory material, as the first line is linked to the third and the second to the fourth. This brings all of the elements of the stanza together into one unified idea. The period in the final line further underlines this connection.
This is also apparent in "Ah! Why, Because the Dazzling Sun":
I was at peace, and drank your beams
As they were life to me
And revelled in my changeful dreams
Like petrel on the sea.
The speaker begins with an image of herself "drinking" sunbeams as they give her some sort of "life" force. She then compares her happiness to that of "petrel on the sea." In the same manner as the other passage, the rhyme scheme ties together the first image ("drank your beams") to the second ("like petrel on the sea") without forcing an artificial comparison or parallel.
This function of rhyme is strongly present in "Long Neglect Has Worn Away." Each of its three stanzas presents a slightly different image of the speaker, moving from the tragic present to the happy past. The ABAB rhyme that Brontë employs gives these quatrains a unity of thought that makes them understandable without being overly obvious.
