The spinster
Belinda is introduced as a woman with no husband and no prospects for marriage. The effect of this on her social worth is negative because of traditional beliefs about gender roles in her community, such that even her best friend accuses her of trying to sneak into Lord Delacour's life just in time for the Lady to die. Belinda is devastated by this wrong judgment of her character and spends the rest of the novel trying to prove to others, to herself, and through the prose to the reader that she is valuable and loving despite her singleness.
Privacy to death
The archetypal quality that defines Lady Delacour is that she is so proper and private that she refuses to tell her own family and friends when she is diagnosed with cancer. This privacy unto the point of death is interrupted by Belinda's curious and clever personality, but not without a fight. Lady Delacour dishonors Belinda for invading her privacy before going to learn in an allegorical manner why humans need friends to support them during difficult times. Death is the ultimate issue, so the dynamic is archetypal, underlining the major themes of isolation and loneliness.
The estate as symbol
The Delacour estate is a symbol for social acceptance because the home assigns everyone a social role. Belinda ends up as a health assistant for her friend during recovery which features her personality—she is giving and selfless. The estate is also a sign for rejection, because Belinda does not merit an estate of her own (a mark against her self-esteem which raises serious feminist considerations) and because she is sent away from her home back into the wilderness of shame and loneliness that defines her life's most intimate pains.
The politeness motif
This novel includes a motif which might actually be unintentional; the social rules that govern polite behavior as so thoroughly accepted that they seem like concrete law. They are in fact purely social construct which means that the motif serves as a contrast to human instinct. That makes sense because politeness is essentially an over-haul of base animal nature. The strictures that govern the characters in this social novel are obvious to the author and her audience, but to the reader, the motif comes across as a floral portrait of human civilization.
Healing as a symbol
The symbolism of healing pairs nicely with the concurrent healing which unfolds between these friends. As Belinda helps Lady Delacour to heal from her battle with cancer, she also heals herself and her friend of the loneliness that makes them skeptical about friendship. Belinda knows from experience the depth of suffering which can be reached when one's most dear friend rejects them—especially without other friends to fall back on. The healing between them brings about a thematic finale to the novel.
