Principles of Political Economy

Among Mill's original theoretical contributions are the equation of international demand, the correct statement of the law of supply and demand as an equation, the concept of noncompeting groups in labor markets, the treatment of economies of scale, the analysis of joint products, the concept of opportunity costs and an advanced theory of interest. "Full of genuine theoretical innovations ... the list of new insights might be extended almost indefinitely." M. Blaug Great Economists Before Keynes. "The most useful [edition] ... indicates the most important changes made by Mill in successive editions and contains a valuable introduction." H.W. Spiegel The Growth of Economic Thought. "The appendix [relates] many items of Millian doctrine ...to contemporaneous, earlier and even later work, and should be studied carefully." J.A. Schumpeter History of Economic Analysis