The “invisible hand” of market prices directs buyers and sellers toward activities that promote the general welfare.

Scottish economist, philosopher, and founder of modern economics Adam Smith wrote in An Inquiry into the Nature and Causes of the Wealth of Nations:

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, or rather necessarily, leads him to prefer that employment which is most advantageous to society. He intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was not part of his intention.

Self-interest is a controlling motivator. As Adam Smith noted long ago, when directed by the invisible hand, self-interested individuals will have a strong incentive to embark on actions that promote the general affluence of a community or nation.

The “invisible hand” to which Smith refers is the price system. The individual “intends only his own gain” but he is directed by the invisible hand of market prices to promote the goals of others, leading to greater prosperity.