Scene Three (Act One)
Polly returns home and is greeted by her very irate parents. Mr. Peachum remarks that after having paid a fortune to raise her, she threw herself away into the garbage. Polly sings a song in an effort to explain why she married Macheath. She talks about all her former "nice" suitors whom she turned down when they proposed marriage. However, when Macheath came along she did not know what to say so she said yes instead and married him. Peachum sarcastically comments that his daughter is now associating with criminals.
Mrs. Peachum calls for some wine and faints, but Polly happily goes and gets her the bottle. Peachum berates his daughter before turning back to business after five beggars walk in. He looks over the five men and helps the first four, but fires the fifth one for eating too much.
Polly meanwhile is rationalizing her decision to marry Macheath. She says she looked over his books and thinks that after a few successful "ventures" she will be able to retire with him to a country house. Peachum tells her that she should do what normal people who get married do, namely get divorced. When Polly argues she is in love, Mrs. Peachum states that Macheath has several other women who can claim to be his wife. She mentions hanging him, and after Polly leaves Peachum realizes that he can get Macheath hanged plus earn a good bounty in the process.
Mrs. Peachum says that she can take care of catching Macheath. She explains that he frequents a brothel and that she can bribe the women there to turn him in when he shows up again. Polly has listened in on the conversation and re-enters the room to tell her mother no to waste her time. She then explains that Mac and Tiger Brown are good friends. Peachum decides to take on Macheath and get him hanged. He sends Mrs. Peachum to the brothel while he and Polly go to see Tiger Brown. The scene ends with all three of them singing a song about the insecurity of the human condition. It discusses the fact that peoples' rights are not secure and that people are mostly poor.
One of the themes that permeates Brecht's work is the concept that business is more important than family. His play Mother Courage epitomizes this concept, with Mother Courage losing her children while she conducts business with the soldiers. The same theme appears here, where Peachum chooses to work with the beggars in spite of the crisis of Polly getting married. Notice also that Polly quickly becomes secondary to the financial prospect of arresting Macheath: "That'll earn us forty pounds" says Peachum.
This theme is further reinforced by the arrival of the five beggars. The scene could easily exist without their appearance, but Brecht inserts them for several reasons. They primarily serve to show how focuses Peachum is on running his business. Second, Brecht introduces one of the most ironic moments in the play by having Peachum fire a beggar. The reader or observer does a double-take at this moment; after all, how can you become an out of work beggar except in a world where capitalism has taken over every aspect of society to such a degree that existence is no longer possible except within the system. Brecht subtly criticizes the excesses of capitalism by showing a world where even begging is a profession.
Love is made fun of by portraying it ironically. Normally a parent would be swayed by arguments of love, but Polly's parents instead advocate divorce for her. When she continues claiming that she is really in love with Macheath, Mrs. Peachum blames the books that Polly used to read. This attitude converts "love" into a form of business deal; there is no point in marrying unless you gain something financially. Polly realizes this and tries to point out to her parents that Macheath is financially well off, however, since he is a competitor to her father, Peachum chooses instead to take this opportunity to ruin Macheath.
Thus Peachum takes on Macheath not because Polly got married but rather because he sees the marriage as an attack against him. "Come to think of it, it shows that the fellow is really audacious. If I give away my daughter,... my house will cave in and my last dog will run off." As far as Peachum in concerned, Macheath has declared a war in the London underworld, and he will try to retaliate, even though he is up against great odds. Mrs. Peachum points out that Mac the Knife is the greatest criminal in London, a man who "takes what he pleases". This does not deter Peachum, who prepares to meet with Brown.