Peachum uses a hunting metaphor in conversation with Filch while discussing Betty, a particularly skilled criminal whom he employs to steal valuable objects from gentlemen:
If none of the Gang take her off, she may, in the common course of Business, live a Twelve-month longer. I love to let Women scape. A good Sportsman always lets the Hen Partridges fly, because the breed of the Game depends upon them. Besides, here the Law allows us no Reward; there is nothing to be got by the Death of Women—except our Wives.
First, Peachum assumes a chivalrous stance, claiming that he likes to help female criminals escape the law and avoid execution. However, he then reveals his true, more selfish motive. Just as a “good Sportsman always lets the Hen partridges fly,” he spares female criminals because “the breed of the Game depends upon them.” In other words, female criminals are particularly valuable to him because they will give birth to and raise future criminals. They are necessary, then, in sustaining his business in the future, as he profits from criminals both by employing them and by turning them in to the law. His hunting metaphor highlights his cold, pragmatic way of thinking: the lives of others are only valuable to him if they are profitable.
Lucy, daughter of the jail keeper, Lockit, uses an extended metaphor that compares Macheath to a rat:
Thus when a good Huswife sees a Rat
In her Trap in the Morning taken,
With pleasure her Heart goes pit a pat,
In Revenge for her loss of Bacon.
Then she throws him To the Dog or Cat,
To be worried, crush’d and shaken.
Here, Lucy speaks bitterly of the man who has betrayed her, imagining herself metaphorically as a “good Huswife” (or “housewife” in contemporary English) who has seen “a Rat” caught in her "trap." Her metaphor is apt: Macheath has indeed found himself in a trap, as he was betrayed to the authorities by the workers in a brothel and now finds himself imprisoned in Newgate Prison.
Further developing her metaphor, Lucy notes that she experiences “pleasure” and excitement in witnessing Macheath’s downfall. Much as the housewife revenges herself on the rat for the “loss of Bacon,” Lucy implies that she has experienced loss at the hands of Macheath, including the loss of her virginity. Concluding the metaphor, she notes that she, like the housewife who throws the rat “To the Dog or Cat” to be eaten, is content to allow her father to execute Macheath, profiting from the bounty on his head.
