Summary
The speaker instructs her addressee to shake off the burden of her thoughts like a tree rustling its branches. She imagines the greenery that metaphorically represents her own thoughts falling to the ground and breaking. After all, when she experiences actual proximity to her beloved, she doesn't need to think about them at all: imagination is replaced by experience.
Analysis
The poem has so far shaped its twists and turns around the built-in segments of an Italian sonnet, and the biggest shift of all (known as the volta) occurs here, in the transition between the opening octave and the closing sestet. Just when the rhyme scheme moves from the established ABBA pattern to a new CDCDCD one, the speaker moves from describing her current troubles to planning an untroubled future. The first eight lines of the poem consisted of the speaker describing her imagined ideal of the addressee, then bemoaning the detrimental effects of that idealization and the gap between fantasy and reality. In the second half of the work, the speaker instead describes in great detail what it looks and feels like when the imagined lover is replaced by a real one. Perhaps the most interesting aspect of this is the fact that, while the speaker is describing what it would be like to be freed from the limits of her own imagination, she is doing so from within a fantasy. That is to say, this second part of the poem consists of her imagining and envisioning what it would be like to no longer rely on her imagination.
Another striking element of her vision is its almost-violent tinge. The speaker pictures a tree (metaphorically standing in for the lover) shaking its boughs, so that the vines around it (metaphorically representing the speaker's thoughts) fall off. But they don't merely fall: they break explosively. In fact, the speaker seems to feel a degree of animosity towards her own thoughts. These images suggest that, for the speaker, fantasy and reality can't truly coexist, and fantasy must be completely, even aggressively, put to an end in order to enable real communion between the couple. The imagery of constriction and suffocation that Browning has previously used disappears, and is juxtaposed with images of air and breath, so that a contrast between the airlessness of fantasy and the freedom of reality is created. In this way, the poem subverts expectations and cliches, since fantasy is usually associated with freedom from the limitations of reality.
