This book traces the evolution of monopoly theories, from Ricardo (1817) to Hotelling (1929) and then to Robinson (1953), and discovers that the economic rent, i.e., extra profit, measure becomes smaller and smaller. Ricardo's economic rent is the whole rent, because land is free, while Robinson's smallest economic rent is caused by a negative demand and a positive supply. This book proves that Hotelling's negative line is not a demand, and argues that a true monopolist can always pass on the entire cost to buyers, to restore Robinson's economic rent to its full Ricardian level. This book thus disproves Robinson's monopoly theory, its monopsony and bilateral monopoly counterparts, and also all the price discrimination theories.