Since some gentlemen have recently made their literary mark without having any learning, modern critics are now claiming that a writer does not require learning. However, the narrator believes that writing—like any art—requires knowledge and study. A writer especially needs to have knowledge of their subject&mash;for instance, if one brought together Homer, Virgil, and Aristotle, they would not write a very good book on the art of dance.
Jones receives two letters from Lady Bellaston. The first asks him whether he arranged to meet Sophia in the drawing room of her house. She warns him that she can hate as passionately as she can love. The second urges him to come and visit her at her house immediately. As Jones is preparing to leave, Lady Bellaston walks in with her dress in disarray. She asks if Jones has betrayed her, and he promises her on his knees that he has not. Suddenly Partridge prances into the room announcing Mrs. Honour's arrival. Tom hides Lady Bellaston behind his bed before Honour enters. Honour prattles on about how Lady Bellaston meets men at a house where she pays the landlady's rent. Then she hands Jones a letter from Sophia. Once Honour leaves, Lady Bellaston emerges from behind the bed, enraged that she has been "slighted for a Country Girl." Lady Bellaston now realizes that Sophia will always occupy first place in Jones's affections, but resigns herself to the second prize. She and Jones decide to camouflage the purpose of his visits by pretending that Tom has come to visit Sophia.
Jones receives a letter from Sophia saying that if he cares for her at all, he should not visit her that day—she is worried that Lady Bellaston suspects something. Jones pretends to be ill so as not to offend Lady Bellaston—he writes an explanatory letter to her ladyship, as well as a letter to Sophia. Lady Bellaston sends a note announcing that she will visit Jones at his room at nine that night. Mrs. Miller asks Tom, very courteously, to leave her house, as she does not approve of him entertaining strange women in his room from ten at night to two in the morning. She is worried about the virtue of her daughters. Jones, slightly annoyed, says that he will not defame her house, but he needs to see whomever he pleases. Tom learns from Mrs. Miller that Partridge has told her about the highway robbery and of Tom's relation to Allworthy. Tom is furious. Partridge blames Mrs. Honour for disclosing these facts.
Nightingale tells Tom that he is also planning to leave Mrs. Miller's house, but without saying farewell. Tom insinuates that he knows this surreptitious mood has some relation to Nancy. He accuses Nightingale of using too much gallantry in order to make Nancy fall in love with him. Nightingale professes that he likes Nancy more than any woman he has ever met, but that his father has prearranged a marriage for him with a woman he has never seen before. He begs Tom not to reveal his secret. The narrator praises Nightingale's honorable character—although this honor, he says, does not extend to affairs of love.
Mrs. Miller invites Tom to tea—she does not wish to part on bad terms with him. She tells him her story, saying that, without Allworthy's assistance, her family could not have survived. Mrs. Miller's father left his three daughters poverty-stricken, and Mrs. Miller was the only daughter to survive. She married a clergyman, who died five years after their wedding. Mrs. Miller reads Tom the generous letter that Allworthy wrote to her at this time. He sent her an initial twenty guineas, then bought her a furnished house, and bestowed a fifty-pound annuity on her. Tom relates his history to Mrs. Miller—without mentioning Sophia. That night Jones waits in his room from nine until midnight, but Lady Bellaston makes no appearance.
Jones is woken by an uproar. He summons Partridge, who relates that Nancy, Mrs. Miller, and Betty are crying in the kitchen. He jokes that there is a new delivery for the "Foundling-Hospital." Mrs. Miller tells Jones that Nightingale—"that barbarous Villain"—has deflowered her daughter, who is pregnant with his child. She shows Tom the letter Nightingale left for Nancy, in which he promises to provide for her and the child. Nancy's reputation might have been preserved if she had not fainted in public after receiving the letter. Nancy has twice attempted suicide, says Mrs. Miller. She admits that she noticed Nightingale's attentions to Nancy, but sincerely thought that he would marry her daughter. Tom resolves to find Nightingale.
Jones finds Nightingale sitting despondently beside the fireplace in his new dwelling—he is worrying about Nancy. He says that he is upset she showed the letter to others—if she had not, her reputation would still be intact and he would not have to worry. Tom tells Nightingale that he should marry her, and Nightingale now admits that he had given Nancy a promise of marriage. He worries, however, about what people will think of him for marrying a "whore." Tom argues that Nightingale's "Honour" will not be reinstated by his rejection of a woman whom he corrupted. Nightingale now argues that he is obliged to uphold his duty to his father. He is to meet the woman his father has arranged for him to marry the following day. Jones insists on meeting with Nightingale's father, and orders Nightingale to visit Nancy. Nightingale suggests that it will be easier for Jones if he tells his father that he is already married.
When Jones arrives at the house of Nightingale's father, the latter is meeting with the father of Nightingale's prospective wife. He thinks that Tom has come to claim a debt from his son. Jones begins by praising Nancy, but without mentioning her name. Nightingale's father, believing Tom to be talking about the lady he wishes his son to marry, is pleasantly surprised by the new attractions of this lady—her beauty, her education, her sweet temper. Tom slowly suggests that it would be silly for Nightingale's father to reject the woman simply because she has no fortune. At this point Nightingale's father asks whether Tom is speaking about Miss Harris. Tom replies that he is speaking of Miss Nancy Miller. Nightingale's uncle enters the room and argues that a parent should have the prerogative to veto a marriage partner, but not to prescribe one. Nightingale was raised more by this uncle than by his father.
Jones returns to Mrs. Miller's house to find everyone rejoicing. Nightingale and Nancy are to be married the next day. Mrs. Miller calls Tom her good Angel. Nightingale's uncle arrives and, in private, congratulates his nephew on his recent marriage. Nightingale admits that he is not actually yet married, and his uncle rejoices at this news. He advises Nightingale to leave Nancy, since he does not have any formal obligations to her until the matrimony. Nightingale tells his uncle that honor demands that one carry through one's promises as well as one's actions. Moreover, he loves Nancy. He reminds his uncle that he always promised to let his daughter, Harriet, choose her own marriage partner. Nightingale's uncle tells Nightingale to accompany him to his lodging so that they can debate the matter more.
Downstairs, Nancy, Mrs. Miller, and Tom are wondering why Nightingale and his uncle have taken so much time for their conference. When the two men emerge, everyone feigns that nothing is amiss. Mrs. Honour arrives with awful news about Sophia. Tom can think of nothing but his "unfortunate Angel."
From Book XIV onwards, the novel gives way to a new writing mode: it becomes in part epistolary, filled with the letters of Lady Bellaston, Sophia, and Tom Jones. This serves to embellish Fielding's eclectic style, which is composed of a pastiche of genres and modes of narration. The narrator flits between essays, dramatic dialogues, and letters. The epistolary mode perhaps heightens the sense of separation that the city introduces into the characters' lives—letters now substitute for people. The irony of Lady Bellaston's letters is that, instead of following the rules of polite conduct, they are often explicitly emotional and lascivious.
Although Lady Bellaston remains a presence in Book XIV, the narrator takes a detour to follow the story of Nancy and Nightingale. Nightingale must learn and adopt Tom's code of honor before he can achieve marital bliss. Nightingale, born and bred in the city, can only think of his external reputation. Tom's insistence on the beauty of a clean conscience provides an alternative model to the false image-based status most of the city characters seek.
Nevertheless, Fielding does not seem to condemn city-dwellers; rather, his attitude in Chapter I seems merely dismissive. A comedic writer does not need to possess a good knowledge of the upper classes, he states, since the upper classes induce boredom.