 Smith's central observation is that, in economic life, it often happens that individuals in pursuit of their self-interest nevertheless contribute to the common good (1776, 484–485).  It is as though they are “led by an invisible hand” (485) to take socially beneficial actions.  For instance, Smith argues that the division of labor is the spontaneous outcome of the human “propensity to truck, barter, and exchange one thing for another” (14).  Humans engage in this activity for self-interested reasons.  But growth in the productivity of labor in a society is largely due to a greater division of labor (3).  It is because of a greater division of labor, Smith contends, that the poorest members of European countries are richer than the richest members of societies in other parts of the world (13). 