There is a recurring story in the media that 150oz Tide detergent bottles are being used as money by criminals. It's a fun story and I can't resist using it to illustrate the idea of liquidity premia. Assume that two types of detergent bottles are held in individual's inventories. Say that they are entirely similar except one bottle is harder to sell than the other. If some unexpected event were to happen, the liquid (excuse the pun) bottle of detergent can be easily sold so as to mobilize resources to deal with the event. The illiquid one can't. This ability to serve as a superior hedge against the unexpected is a valuable service. Even if the unexpected doesn't occur, anyone holding the liquid bottle will face less stress and unease over time knowing that they are positioned to deal with any eventuality. A forward-looking individual will anticipate this stream of uncertainty-shielding services provided by the more saleable bottle, discount these streams into the...