Pop quiz: Which classic Brit Lit poem begins with the poet talking about a couch?
Answer: William Cowper's "The Task” (1784), which also happens to be the source for Jacobs's chapter title, "The Loophole of Retreat":
'Tis pleasant through the loopholes of retreat
To peep at such a world; to see the stir
Of the great Babel and not feel the crowd;
To hear the roar she sends through all her gates
At a safe distance, where the dying sound
Falls a soft murmur on the uninjured ear.
Here, the loophole represents a place from which the poet can view the world’s misfortunes. Not so much for Linda, who experiences the loophole as a particularly intense form of slavery, so much that it becomes a symbol for the captivity of Southern slaves. Separated from her family, physically uncomfortable, voiceless, and so powerless that she can't even move, Linda is getting a crash course in what slavery is like for the majority of slaves.
But maybe the reference to Cowper (pronounced "cooper," BTW) can let us put an unexpected spin on Linda's crawlspace. Sure, it's a hellhole of rats, ants, and snow, but it's also protection from Dr. Flint, and a place where she can keep an eye on her kids.
It gives her a new, or at least deeper, perspective on slavery, since, as she says, "Southerners have the habit of stopping and talking in the streets, and I heard many conversations not intended to meet my ears" (21). It's a perch from which she can really come to terms with how awful slavery is.
So, in a strange way, the attic also comes to represent certain possibilities within slavery. The most important aspect of the attic is that Linda chooses her confinement. She would rather lie immobile for seven years than allow Dr. Flint possession of her body. In this sense, the crawlspace becomes a symbol of Linda’s self-possession and resilience in the face of adversity.