In a speech delivered last week, Federal Reserve Vice Chairman Donald L. Kohn addressed a theory to which I am partial: the theory that low real interest rates have contributed to the continued rise in prices of agricultural and mineral commodities, including oil, over the last year. He said:

It is hard to remember now, but mineral and agricultural commodities were considered passé less than ten years ago. Anyone who talked about sectors where the product was as clunky and mundane as copper, corn, and crude petroleum, was considered behind the times.