Based upon those notions of self-interest and public interest and the bringing of both into harmony, according to Adam Smith, how would a market economy accomplish that harmony about which he describes? What is government's place in that market economy?

Think about society's need to choose amongst competing resources and goals. How does personal gain affect choices by individuals and government? Opportunity costs. While we want to do one thing, we can't do others based upon scarcity and opportunity costs. Resources are finite. What about incentives as opposed to free offerings? What about trade?