Suddenly I heard Rose's voice from the kitchen. "See, I told you what mischief you were causing," she hollered, as Milton broke into a deep-throated laugh.

"The withholding tax was my fault," he explained. Apparently, as a young economist working for the Treasury Department, Friedman helped design the federal withholding tax. It was not a totally indefensible act though, he said. "Without it, we would not have had a steady flow of money into the Treasury to fight World War II."

Rose seemed affectionately unconvinced. The moment captured what I observed over the course of our conversations: an incredible relationship between two brilliant, strong-willed persons. Theirs was a true collaboration built on deep mutual respect and love.

Milton Friedman may be best remembered for his theory that money supply and interest rates are more important in contributing to a healthy economy than government fiscal policy. At the time he began writing about monetary policy, the theories of British economist John Maynard Keynes, who believed government spending could stimulate the economy, were widely accepted.

But it was Friedman's championing of the free market -- along with his ability to translate complicated economic theories into plain English and communicate them to a broad audience -- that made him such a formidable public figure. He was, above all, a great teacher. The world is a poorer place with his passing.