What we have forgotten may sometimes be more relevant than what we know. In my book, Railroading Economics, I showed how the late 19th century and early 20th century economists who were studying the railroads are much more relevant for understanding a modern economy with production largely based on high fixed costs and low marginal costs. Many of the same economists, including John Bates Clark, also produced a lot of work in conventional microeconomic theory, which became incorporated in modern thought. Ignorance about their other work made modern economists far less prepared to understand the modern information economy. Michael Perelman