When asking for help, appeal to self interest

"It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest." Adam Smith

Is law 13 therefore implemented through self centred productivity? If the butcher lets say borrows from the bank to open a chain of butcheries, his productivity increases simultaneously to his appeal to the customers need for meat. How is Law 13 actualized? Through increased productivity?