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