Using simple but rigorously defined mathematical models, Thomas Quint and Martin Shubik explore monetary control in a simple exchange economy. Examining how money enters, circulates, and exits an economy, they consider the nature of trading systems and the role of government authority in the exchange of consumer goods for storable money; exchanges made with durable currency, such as gold; fiat currency, which is flexible but has no consumption value; conditions under which borrowers can declare bankruptcy; and the distinctions between individuals who lend their own money, and financiers, who lend others'.