In a letter to Lucy, Eliza relates a flirtatious conversation with Sanford, who is trying to sway her against accepting Boyer's proposals. Sanford says that if she marries Boyer, Eliza will spend the rest of her life seeking favor with gossipy townspeople eager to find fault in a pastor's wife. Trying to keep Sanford on his toes, Eliza responds haughtily that,
[...] as to the praise or censure of the populace, I hope always to enjoy that approbation of conscience, which will render me superior to both.
In this passage, Eliza says that her strong moral compass will prevent her from being affected by other people's approval or disapproval. This is an example of verbal irony, because what Eliza says does not at all reflect her mental state. Contrary to her assertions to Lucy, Eliza is driven by a desire to be appreciated and esteemed by others, especially men. Sanford, who instantly perceives this character trait in her and remarks on it in his own correspondence, showers her with praise in order to seduce her; his behavior renders Eliza vulnerable to him in ways that friends like Lucy, who care less about appearing beautiful or charming, are not. Moreover, Eliza inwardly agrees with Sanford's dire predictions about marriage to Boyer; she's reluctant to accept the pastor's proposals precisely because she fears life with him would be boring and constrained.
This passage is also an example of situational irony, because Eliza's assertion is at odds with the social circumstances in which she lives. Whether or not she personally values the "praise or censure" of others, Eliza cannot afford to be truly indifferent to other people's opinions. In a society in which women's fates are dependent on the kind of man they marry, and securing a respectable marriage depends on cultivating a spotless reputation, women like Eliza and Lucy must be acutely attuned to what other people think of them. In fact, Eliza meets a tragic fate precisely because she prioritizes the opinion of unserious suitors like Sanford over her moral reputation, thus dooming her prospects of making an advantageous marriage.
In a final letter disavowing his love for Eliza and ending their shaky engagement, Boyer takes the opportunity to criticize her appearance and behavior, writing that,
There is also an unwarrantable extravagance betrayed in your dress. Prudence and economy are such necessary, at least, such decent virtues, that they claim the attention of every female, whatever be her station or her property [...] Too large a portion of your time is devoted to the adorning of your person
Representing a perverse and hypocritical change in Boyer's feelings, this passage is an example of situational irony. In fact, Boyer was initially drawn to Eliza precisely because of her charm and the polished appearance to which she devotes so much time: in his first letter to Mr. Selby, he praises her "elegant person" and "polished manners." The discrepancy between those two letters shows that Boyer doesn't really care about the time Eliza spends on her appearance; rather, he's angry that she won't make herself available to him and obviously prefers to marry Sanford. Once Boyer realizes that he's not Eliza's first choice, he resorts to shaming her for not appearing to prioritize "prudence" and "economy," two virtues that women in their society are expected to uphold at all times. This moment in the novel illuminates the double bind faced by women like Eliza, who must attract men through beauty and social graces while appearing to care only about modesty and propriety.
