LitCharts assigns a color and icon to each theme in The Beggar’s Opera, which you can use to track the themes throughout the work.
Moral Corruption and Hypocrisy
Gender, Love, and Marriage
Class, Capitalism, and Inequality
Opera, High Art, and Performance
Summary
Analysis
Lucy again asks Polly to drink, but Polly declines. Lucy tells Polly not to be squeamish about drinking “Strong-Waters” in front of a woman and warns that she will be offended if Polly refuses. Then, Polly sees Macheath in the distance: he has been arrested again and is returning to Newgate. She drops the glass of cordial and says she is even more distraught now. Lucy privately tells the audience that she’s happy Polly didn’t drink, because “she was not happy enough to deserve to be poison’d.”
Macheath’s arrest shows that Polly has not taken him away from Lucy, and Lucy will no longer win him back if she kills Polly. Thus, it permanently shifts the play’s tone and plotline, and Lucy’s murder attempt turns out to have been a red herring. (Still, it built up a sense of suspense and dramatic tension that will carry on for the rest of the play.)