Scene Four (Act Two)
Polly arrives at the stable where Mac is currently living and tells him that he must leave immediately. She says that her father threatened Brown and forced him to issue an arrest warrent for Mac. Mac does not believe her until she produces the list of charges they have against him; it is a very long list with everything from murder to arson to underage sex. Macheath agrees that he should flee and tells her to take over the business for him. She tries to be sentimental but he brusquely interupts her and shows her the account ledgers. Mac then reads off a list of his men and tells her which ones to promote and which ones to send to jail.
He informs Polly that he is planning on switching into banking soon since it is safer and more reliable. He plans to turn the entire gang over to Tiger Brown once he does not need them anymore. Polly asks him how he can look his men in the eye and still plan on hanging them, but they walk in before he can complete his answer. Mac immediately acts friendly towards them. He tells them to go ahead and work without him during the Coronation. He lastly puts Polly in charge of the business.
Polly tries to take charge, but Matthew is reluctant to work for a woman. She turns on him and screams that if he ever says anything against her she will have the other men rip him to shreds. The other men applaud her. Mac then berates Matthew for drinking too much. He asks Matthew who set the Children's Hospital on fire in the last week (alluding to the seven dead children mentioned in the prologue). Matthew at first takes credit, but the other men all credit Macheath with the crime, thereby forcing Matthew to agree with them.
After the gang leaves Polly and Mac remain alone. Polly pleads with Mac to leave immediately and not to look at any other women while he is away. She is desperate to have him stay with her and laments the short time they have been together. Polly tells Mac that she had a dream in which she way the moon and it looked like "a worn-down penny". Mac promises not to forget her and leaves. Polly then comments that he will never return and sings a song about losing her lover.
The fundamental theme that emerges is that business trancends love in this amoral, capitalist world. Mac the Knife tells Polly, "All right, if I've got to go away, you'll have to run the business." In spite of her tears, he sits down and goes over the ledger books with her. This replacement of love with business is a direct attack on capitalist society in which emotions are subordinated to fiscal transactions.
The reduction of love to mere business is furthered by Polly in her dream. She remarks that she dreamt about the moon, a symbol of her and Mac's love. The moon is equated to a "worn-down penny." This gives love two meanings and references, the first being that it equates love with capitalism. Second, love is compared to something old and not worth very much. This belief that love is worthless is held by all of the characters except for Polly who seems to the only character struggling to achieve worthwhile emotions. As the end of the chapter indicates, even she readily capitulates to the capitalist ideal and gives up on her love.
Mac is very adamant about taking credit for mistakes, especially mistakes committed by his men. This is a power struggle. The man who can take credit for mistakes can also takes credit for successes; Macheath is playing the part of a capitalist owner reaping the benefits of his ownership. Notice also that Brecht makes the interesting comparison to a university professor claiming credit for the students' work. Brecht is essentially accusing universities, who claim to be immune from capitalist influences in the sense that economic motive does not underlie their research, of being in some ways worse than the average factory owner.
Interlude (Act Two)
Mrs. Peachum and Low-Dive Jenny are together. She has convinced Jenny to turn Mac the Knife in to the police for ten shillings. When Jenny argues that Mac will not show up if he is being hunted by the police, Mrs. Peachum sings the "Ballad of Sexual Obsession". She describes that some men cannot control their urges and must go to prostitutes to satisfy themselves.
This interlude is actually quite biographical. Brecht was usually unable to control his own sexual urges, having several mistresses at one time and also experimenting in bisexuality. The song was not sung in the original performance because the actress refused to perform it, but it does serve to foreshadow the fact that Mac the Knife will inevitably go to the whores. It also lends a new symbolism to the nickname Mac the "Knife", which now receives a sexual meaning, referring to the number of women Mac has had sex with.