The lyrics of the opening song in John Gay's The Beggar's Opera establish the main social conflict of the play: despite the different levels of respect and privilege afforded the different vocations ("through all the employments of life"), all people are capable of bad behavior such as dishonesty, theft or infidelity. "Each neighbor abuses his brother…all professions be-rogue one another."
Essentially the theme is introduced to demonstrate the general untrustworthiness of the characters. Peachum, the businessman/merchant, not only sells goods honorably but buys stolen ones. He further insists that lawyers should defend all men in the same manner since they are all capable of wrongdoing. He then implies that even clergymen are as likely to be dishonest as politicians are. "The priest calls the lawyer a cheat; the lawyer be-knaves the divine; and the statesman because he's so great, thinks his trade as honest as mine."
Meanwhile the main protagonist, Macheath, the highwayman, seduces women with his charming personality and winds up in jail. His character demonstrates that the main power possessed by the poor is their sheer force of personality, since money and social prominence may elude them. Macheath is eventually released before his scheduled execution, because he persuades his captors that he deserves to live, and in part because his lover Polly, Peachum's daughter, begs her father to spare his life. The message is that social dominance in the form of wealth or class is useful but that charisma and persuasion are also significant forms of currency.