In February 1982, 1 was sitting in a classroom at the University of Chicago, in a graduate course in public finance taught by Arnold Harberger. He was explaining the economic consequences of certain provisions in U.S. tax law that allow producers of oil and gas to use percentage depletion rather than cost depletion. I found myself riveted by this material, since I had worked on a legal case involving percentage depletion for over a year, as a lawyer in New York. I knew (or so I thought) as much as a lawyer can know about the tax provisions, their legislative history, and the policy arguments for and against percentage depletion. Yet that class gave me insights about the consequences of the subsidy that is percentage depletion, the merits of the policy arguments, and the different analyses of the tax issues by accountants, lawyers, and economists that I would never have gained if I had spent my entire career in this area of practice as a lawyer. It was for me a powerful and strangely affecting experience. Somewhat later I took a course in the economics of regulation from Sam Peltzman. One day he explained that the problem of pollution can be viewed as one of incomplete property rights, to which economists had proposed an elegant solution: creating marketable licenses to pollute. Hearing this, I could not suppress a smile, since I knew from my experience in law and business that, for political reasons, such a proposal would have no chance of being adopted..