The Subjectivity of Truth
Sister is a notorious example of what is known in literature as the “unreliable narrator.” This unreliability does not necessarily castigate her as an outright liar nor does it automatically implicate her narrative as false. Since everything that the reader knows is filtered through Sister’s first-person dramatic monologue, nothing she says is verifiable. Beyond that, Sister does perhaps unwittingly draw suspicion upon her reliability by straining just a little too hard to convince the reader that everyone is against her. A modest level of paranoia creeps through Sister’s account, thus calling into question just how much of what she has written can be termed objectively factual. On the other hand, it must also be accepted that everything quite possibly happened exactly as Sister describes.
Declaring Independence
The story takes place on a stifling hot 4th of July, thus creating historical context for Sister’s decision to declare her own independence from the stifling influence of family. Like the colonists in 1776, Sister expresses a feeling of being constricted and trapped by external authority imposing their will upon her and threatening her autonomy. The escape to the post office represents the slightest possible improvement over her daily living conditions, but is equitable to the establishment of an independent state in terms of seeking to become more self-dependent.
Communication
Sister does not tell us about why she moved to a boarding house or why she moved to her neighbor’s barn or why she moved to another city. She specifically finds a sense of independence at the local post office because that location is thematically significant. The post office is the epicenter of communication between local resident and outside world. By moving to the post office, Sister is symbolically seeking to move closer to learning how to communicate because back home everything has fallen into chaos precisely due to a communications breakdown. Between the petty bickering, the shifting allegiances, the mysteries of relationships with those outside the family and the outright lies and deceptions, the house from which she moves is pretty much a definitive example of how lack of communication engenders disorder.
