In an early letter to Mr. Deighton bragging about his ability to deceive others about his character, Sanford makes an allusion to the Greek sea god Proteus, writing that
I am a mere Proteus, and can assume any shape that will best answer my purpose.
In Greek mythology, Proteus is notable for his ability to constantly change his shape in order to avoid being captured, much as the sea often changes in appearance and behavior. Sanford makes this allusion during a passage in which he confesses to "maneuvering," or manipulating Eliza's feelings through his own charm. Sanford admits that such behavior may seem "out of character" given his genuine feelings for Eliza. However, like Proteus, he is able to present different versions of himself to society depending on which will best serve his hidden agenda of seducing Eliza.
In general, the novel tends to portray constancy, especially among female characters who remain friends despite circumstances that threaten to divide them, as a crucial virtue. Accordingly, this evidence of Sanford's fickle nature contributes to his characterization as a villain early in the novel. This passage is also remarkable for showing the different standards men and women face when it comes to upholding a virtuous reputation. Young women like Eliza, in search of respectable husbands, are under pressure to demonstrate good and unchanging character through their public and private behavior. Eliza ultimately incurs the disapproval of her friends and a marriage proposal by behaving inconsistently toward Boyer and flirting with Sanford when he isn't around. For Eliza to be described as "a mere Proteus" would be an extreme insult; but Sanford feels unashamed about cultivating the same attributes for which Eliza is punished, and he maintains high standing in society despite general awareness of his shifty character. Boasts like this one in Sanford's private correspondence underline how women in post-Revolutionary society are harmed by lax standards for men's behavior.
Discouraging Eliza from flirting with Sanford, Mrs. Richman makes an allusion to Samuel Richardson's novel Clarissa. In a private conversation, she says,
I do not think you seducible; nor was Richardson’s Clarissa, till she made herself the victim, by her own indiscretion.
First published in 1747, Clarissa is a wildly successful novel about a young woman named Clarissa who, despite her virtuous character, gets involved with an untrustworthy libertine who fails to fulfill his promise to marry her. Like The Coquette, Clarissa is an epistolary novel; in fact, Richardson had helped to popularize the epistolary form with his 1740 novel Pamela. All three novels explore similar themes around flirtation, sexual transgression, and male perfidy.
Both Pamela and Clarissa would have been very popular with Anglophone audiences by the time the action of The Coquette takes place in the late 18th century. So it makes sense that Mrs. Richman references Richardson's work when trying to warn Eliza against proceeding with Sanford. However, like Clarissa, Eliza is eventually seduced despite her virtuous character and good intentions; in that sense, this comment from Mrs. Richman serves as a moment of foreshadowing as well.
Clarissa is known for endorsing conservative norms about women's roles while also painting a nuanced portrait of female sexuality and the limited choices female characters have within a patriarchal society. By aligning her novel with Richardson's, Foster is hinting at her own subversive goals to the reader.
