Barrett Browning's artistic challenge in "Sonnet XXIX" is to depict the feelings that come upon her when she is separated from Browning; by extension, the poem applies to anyone who thinks about his or her absent beloved with longing and anticipation of his or her return. Barrett Browning's method is to describe the workings of her mind in organic terms: thoughts are like "wild vines" that wind about the image of Browning, here likened to a tree.

Barrett Browning's comparing her thoughts of Browning to vines that "twine and bud" about him suggests the degree to which his absence (regardless of length) has affected her: "twine" implies that her thoughts continually move in steady ways, while "bud" suggests that they continually grow. One thought of Browning leads to a second, which leads to a third; thoughts engender more thoughts, just as vines keep winding and budding...