The changes of the last four decades, which make up “The Industrial Revolution in America,” have left their mark upon the economics of the schools. If there was a time when the thought of the professed economists was a thing apart from the common sense of the age, it ended with the coming of industrialism. Differ as it may in phrase, in method, and in statement, the economics in solid and dull treatises reflects, as it has always reflected, the opinions of the laity. If there were agreement among the sorts of men who gather at ball games and in smoking cars, the books on economics would all read alike. But when the plumber differs from the banker and the scrub woman refuses to take her ideas from the coupon clipper, it is futile to expect mere economists to agree. To some, the classical doctrine still serves as a sabbatical refuge from modern problems. Others, who “specialize” in trusts, tariffs, and labour are too busy being “scientific” to formulate general opinions. Still others insist upon creating a new economics concerned with the problem of directing industrial development to appointed ends. Each of these schools has a membership large enough to allow dissension within the ranks. The revolt against the classical economics began when it encountered modern fact. Beyond the pale of doctrine taught by certified theorists appeared studies upon corporations, international trade, railway rates, craft unionism, and other matters of the newer fact. For a time those who studied these subjects were content to describe in superficial terms the results of their observations. But as facts accumulated they provoked generalizations at variance with the accepted principles of the older competitive theory. At the same time the rise of a newer history concerned with development rather than chronology, a new ethics that recognized the existence of a social order, and a new psychology that taught that the content of men’s behaviour is poured in by the environment, together made the foundations of the older economics very insecure.