We dive into Part Four of Human Action with Professor Jeffrey Herbener, Chair of the Economics Department at Grove City College. This is a fantastic discussion of money and market exchange, with Mises proving timely as ever given the current financial meltdown and crazed response from Washington. Dr. Herbener and Jeff Deist cover catallactics and how imaginary constructs help us understand basic economics; markets as a system of social cooperation; how ordinal preferences find expression in money prices; the structure of production; consumer sovereignty; Mises's conception of monopoly; and the various media of exchange which complicate what ought to be the market's provision of commodity money. Use the code HAPOD for a discount on Human Action from our bookstore: Mises.org/BuyHA. Human Action: Mises.org/HumanAction Bob Murphy's Study Guide to Human Action: Mises.org/Study