"The Theory of Prosperity" may be regarded as a fusion of the economic philosophy which the author summarized in his "Dynamic Economics" with the results of the studies in social psychology presented in "The Theory of Social Forces" and "The Development of English Thought". But such a characterization is only partly true. Professor Patten has a well-earned reputation for originality, which his latest work will not diminish. In -act, there is an element of unexpectedness in Professor Patten's developments of his own theories which adds to the interest of any new work coming from his hand. The two general divisions of the book treat of "Income as Determined by Existing Conditions," and "Income as Determined by Heredity." "Economic forces rise out of existing conditions and exert an influence on the present race of men. Past environments influence through heredity, morals and traditions." It is the first of these two general divisions which is of greater interest to the economist. Professor Patten believes that the traditional classification of income as wages, rent, and profits has outlived its usefulness, since the recipients of these three forms of income no longer constitute distinct social classes. "These shares, instead of being distinct funds, are the bases of three viewpoints from which income may be regarded." Accordingly, the three chapters forming the first division of the book are entitled "Work and Pay," "Monopoly Advantage," and "Investments." In the first chapter are presented the ideas of cost, sacrifice, expense, producer's surplus, consumer's surplus, utility, and value with which readers of Professor Patten's earlier works are familiar. New emphasis, however, is given to the idea that production and consumption cannot be balanced against each other and measured in terms of pleasure and pain. The effort of production is not necessarily, nor even normally, painful. Consumption should give a surplus of energy to be used in production. A painless and perpetual round of "production, consumption, rest, revival of energy, and renewed production" is thus possible. Pain arises only when the working day is extended beyond the normal, or when surplus energy is wasted. Labor is thought to be disagreeable only because of historical associations of servility. Many readers, however, will place an interrogation point after the statement that " it is not correct to count the social penalties imposed on workers among costs." Having endeavored to show that costs have little to do with fixing the rate of wages, Professor Patten develops a new theory of wages, based on the option which the best laborers in each group have of remaining where they are or entering another group. "The movement from industry to industry that holds up the rate of wages is among the strong of each group." Although his particular conclusions may not find ready acceptance, there can be no doubt that Professor Patten has rendered a service in emphasizing the looseness with which the pleasure and pain formula, as ordinarily used, fits the facts of economic life. In the chapter on "Monopoly Advantage" Professor Patten takes exception to the idea that marginal cost has anything to do with price. Approaching the subject, characteristically, from the side of consumption, he finds that rising prices are limited by the consumers' power of substitution. –The Journal of Political Economy, Vol. 11