 Monetary history may be viewed as a process of improvement with regard to these functions of money (Ferguson 2008, Weatherford 1997). For example, some early societies used certain basic necessities as money, such as cattle or grain. Other societies settled on commodities that were easier to handle and to tally but with more indirect value, such as clamshells and precious metals. The archetypical form of money throughout history are gold or silver coins—therefore the commodity theory is sometimes called metallism (Knapp 1924, Schumpeter 1954).  Coinage is an improvement on bullion in that both quantity and purity are guaranteed by some third party, typically the government. Finally, paper money can be viewed as a simplification of the trade in coins.  For example, a bank note issued by the Bank of England in the 1700s was a promise to pay the bearer a certain pound weight of sterling silver (hence the origin of the name of the British currency as “pounds sterling”).