The invisible hand

The invisible hand is a metaphor coined by the economist  Adam Smith. Once in The Wealth of Nations and other writings, Smith demonstrated that, in a free market, an individual pursuing his own self-interest tends to also promote the good of his community as a whole through a principle that he called “the invisible hand”. He argued that each individual maximizing revenue for himself maximizes the total revenue of society as a whole, as this is identical with the sum total of individual revenues.

http://en.wikipedia.org/wiki/Invisible_hand