STATIC ECONOMICS AND BUSINESS FORECASTING 13 
cannot go far. Nowhere is a grasp of general economic theory 
more necessary than in the study of money and banking. The 
theory of value and prices is essential in the study of marketing. 
The theory of wages is necessary to the study of labor problems. 
The backbone of the study of rate-making—an essential part 
of the subject of transportation—is to be found in the static 
doctrine of joint costs, which is not to be understood apart from 
the general theory of value and price. The whole course of what 
has gone before is concerned with showing how vital the general 
body of economic theory is to the study of the business cycle. 
Teachers of economics are emphatically unfair to “the young 
man” if they do not give him “a thorough grounding in theory.” 
The economist’s peculiar service in the study of business problems 
consists in his ability to see the whole business situation and 
the interrelations among businesses, where the well-informed man 
in a particular trade sees only a part. It is the purpose of 
general theory to give the student this comprehensive point of 
view.