MONEY is perhaps the most basic building-block in economics. It helps states collect taxes to fund public goods. It allows producers to specialise and reap gains from trade. It is clear what it does, but its origins are a mystery. Some argue that money has its roots in the power of the state. Others claim the origin of money is a purely private matter: it would exist even if governments did not. This debate is long-running but it informs some of the most pressing monetary questions of today.
http://www.economist.com/node/21560554