As Clarissa Dalloway sets out in the morning to buy flowers for her party, she recalls the feeling of setting out for the day when she was 18 and still living in Bourton. As she thinks about how "fresh" the morning air always feels to her, the narrative uses auditory and tactile imagery to metaphorically compare going outside to "plung[ing]" into refreshing water:
What a lark! What a plunge! For so it had always seemed to her when, with a little squeak of the hinges, which she could hear now, she had burst open the French windows and plunged at Bourton into the open air. How fresh, how calm, stiller than this of course, the air was in the early morning; like the flap of a wave; the kiss of a wave; chill and sharp and yet (for a girl of eighteen as she then was) solemn, [...].
The "squeak of the hinges" emphasizes Clarissa's departure from the stuffy, pent-up environment of her home, calling attention to the fact that she has decided to go buy the flowers herself instead of sending someone else to do it. There's almost a sense of adventure to this moment, as she feels like she's "plung[ing...] into the open air" like she used to when she was a young woman. This metaphorically ties leaving home to the idea of jumping into refreshing water, which is "chill and sharp"—that is, somewhat shocking and bracing, even if it's also revitalizing and exciting. The combination of auditory and tactile imagery with metaphor in this passage thus frames Clarissa's outing as a rejuvenating experience and, in doing so, spotlights her strong appreciation for the beautiful world around her.
After Richard Dalloway and Hugh Whitbread leave Lady Bruton's luncheon, she lies down to take a nap, and the narrative metaphorically focuses on what happens to their relational connection as she sinks into sleep and the two men recede into the distance:
And they went further and further from her, being attached to her by a thin thread (since they had lunched with her) which would stretch and stretch, get thinner and thinner as they walked across London
This metaphor suggests that Richard and Hugh are "attached" to Lady Bruton by a "thin thread" that becomes progressively "thinner"—or weaker—the farther they get from her house. This is an illustration of the way certain experiences feel like they slowly fade away after ending, lingering in the minds of the participants but progressively becoming less and less immediate or relevant. What's more, the idea of being "attached" to somebody after having lunch with them aligns with the novel's interest in the characters' social associations. According to this metaphor, sharing lunch with people in this social context (British upper-class society in the 1920s) is like forming an attachment to them.
To that end, the passage goes on to use a simile that cements the idea of relational connections as actual physical attachments:
[...] as if one’s friends were attached to one’s body, after lunching with them, by a thin thread, [...]
The passage also uses some auditory imagery, saying that this "thin thread" slowly becomes "hazy with the sound of bells, striking the hour or ringing to service"—a description that emphasizes the fading feeling of connection while also hinting at the "hazy," satisfyingly faint feeling of nodding off to sleep. After all, this entire image of Richard and Hugh being connected to Lady Bruton by a thread ultimately comes from Lady Bruton's half-asleep mind, and the passage begins to reflect the strange, highly figurative ways that people tend to think when they're drifting out of consciousness. In keeping with this, there's yet another simile that reminds readers that all of these thoughts are playing out in Lady Bruton's sleepy mind:
[...] as a single spider's thread is blotted with rain-drops, and burdened, sags down. So she slept.
Basically, the whole progression vividly puts readers into the feeling of falling asleep, a state in which it's possible to continue thinking about something that has just happened before inevitably losing hold of the entire thought and "sag[ging] down" into a full slumber.
