In a letter to Lucy at the beginning of the novel, Eliza uses a metaphor to express her confidence in the strength of her many friendships. She writes that,
Fortune, indeed, has not been very liberal of her gifts to me; but I presume on a large stock in the bank of friendship.
In this sentence, Eliza compares the idea of friendship to a "bank," and the personal bonds she has formed with people like Lucy to "stock." In other words, she's saying that friendships are similar to money or other financial resources, in that she can draw on them in times of need.
Eliza makes this remark as a humorous witticism in a generally lighthearted letter. However, the metaphor also speaks to the transactional nature of many relationships within this hierarchical and conservative early American society. This is especially evident in the calculations women like Eliza have to make when searching for a husband. Openly desiring a wealthy husband, as Eliza initially does with Sanford, is considered unseemly; but women have to keep economics at the forefront of their minds, because they can't work and will eventually rely on a husband completely. Meanwhile, men like Sanford explicitly select brides from rich families in order to enrich themselves. While Sanford's behavior is generally considered unscrupulous, it is not stigmatized as much as Eliza's desire to find a wealthy match.
The metaphor also hints at the extent to which women in this novel are dependent on friends and acquaintances to maintain their moral reputations, secure their place in society, and expose them to eligible men. Sometimes this reliance on friends is portrayed positively, as when Mrs. Richman tries to help Eliza find an eligible husband, or when Julia, Lucy, and Mrs. Wharton collaborate to nurse her through a deep depression. At other times, that dependence is rendered negatively, as when neighborhood gossip tarnishes Eliza's reputation and hastens her fall from grace.
While friendship is sometimes a resource on which Eliza can rely, it is also a force that constrains her and limits her opportunities. Ultimately, this metaphor contributes to an ambivalent portrayal of women's romantic and platonic relationships in post-Revolutionary America.
In a letter to Eliza warning her of the danger posed by Sanford's seductions, Lucy uses a metaphor to describe the value of a woman's social reputation. She writes to Eliza that
No female, whose mind is uncorrupted, can be indifferent to reputation. It is an inestimable jewel, the loss of which can never be repaired.
In this passage, Lucy compares a woman's reputation to "an inestimable jewel" that is key to her social success. She's expressing a widely held belief that guides the actions of most of the novel's female characters. Virtuous women like Julia, Mrs. Richman, and Lucy herself are careful to appear chaste, modest, and selfless at all times because they know their reputations are crucial for attracting respectable, prosperous husbands. In fact, concern for her own reputation dictated Eliza's behavior for most of her life, until Mr. Haly's death released her from an unwanted engagement and caused her to rebel against these oppressive expectations.
The novel's narrative arc seems to affirm this metaphor. Eliza's flirtatious demeanor and lax approach to others' perceptions of her cause Sanford to see her as an easy catch; and as Eliza's affair and unorthodox behavior incur social judgment, her prospects for marriage and a secure life correspondingly decline. Eliza's final decision to banish herself to give birth among strangers is evidence of her belief that the loss of her reputation "can never be repaired": without good social standing, she doesn't think it's worth living in her society.
However, many of Foster's stylistic choices undermine this conception of reputation. The author depicts Eliza as a highly sympathetic character, encouraging the reader to root for her despite her failure to guard her reputation. She also casts Sanford as a deliberately malicious villain, arguing that he bears most blame for Eliza's death. And in the final chapters of the novel, she focuses on the female friends who mourn Eliza despite her transgressions, rather than those who would judge her behavior. These choices amount to an implicit protest against the use of "reputation" as the determining factor of a woman's character and worth.
In a letter to Eliza warning her to be wary of Mr. Sanford, who has continued to pursue her despite marrying another woman, Lucy uses a metaphor to describe the danger he poses, writing that
[...] marriage is but the cloak of his intrigues.
In this passage, Lucy compares Sanford's status as a married man to a "cloak" that protects him from public scrutiny even as he behaves badly. This dramatic and ominous language heightens the sense of Sanford as a villain, and makes Eliza's inability to perceive his true character all the more tragic.
More broadly, the metaphor also highlights how marriage functions differently for men and women in post-Revolutionary America. Initially betrothed to a much older man she doesn't love, and then pressured to marry the unimpressive Mr. Boyer, Eliza understandably sees marriage as a trap. Her first engagement would have pushed her into an unwanted caretaking role; and even with a more enviable partner such as Mr. Boyer, she would have to spend her life supporting his career and conforming to social expectations for a pastor's wife. Eliza's experience with various suitors shows that in this society, marriage forces women to adapt to their husbands' desires and fundamentally circumscribes their lives.
By contrast, men can profit socially and financially from marriage. Men like Sanford, who purposely marry for money, can enrich themselves and gain more autonomy through marriage, whereas women would give up control of their money to their husbands upon marriage. For Sanford, who was viewed with suspicion as a rake upon his first introduction to society, getting married provides a boost to his social status without actually preventing him from pursuing Eliza. In this sense, Lucy's metaphor is both an indictment of Sanford personally and of the different experiences of men and women within the institution of marriage.
