Ira Glass speaks with several members of the Planet Money team, who all found themselves—in the course of their reporting—independently asking the same stoner-ish question: What is money? Ira and Planet Money producer Jacob Goldstein discuss a pre-industrial society on the island of Yap that used giant stones as currency. The book that Jacob read about Yap is called The Island of Stone Money.

Our crack economics duo, Producer Alex Blumberg and NPR International Economics Correspondent Adam Davidson, on how a dead, slutty, elitist British man, John Maynard Keynes, is about to take over the American economy. President Obama's new stimulus plan relies on Keynes'; theory, which says that government can spend its way out of a downward economic spiral.