Background information: This passage, about self-interest, is from Adam Smith's The Wealth of Nations, which was published in 1776.
Every individual is continually exerting himself to find out the most advantageous employment for whatever capital he can command. It is his own advantage, indeed, and not that of the society which he has in view. But the study of his own advantage naturally leads him to prefer that employment which is most advantageous to the society.
According to the passage, how do people pursuing their own self-interests benefit society?