" That is why, as Adam Smith put it, an individual who "intends only his own gain" is "led by an invisible hand to promote an end which was no part of his intention. Nor is it always the worse for the society that it was no part of it. By pursuing his own interest he frequently promotes that of the society more effectually than when he really intends to promote it. I have never known much good done by those who affected to trade for the public good. "

― Milton Friedman , Free to Choose: A Personal Statement