The author points out that the theory of agricultural of THÜNEN, industrial of WEBER, as well as the great number of investigations that have enriched the studies on if developed in every aspect, are nevertheless disconnected from general economic theory.
In view of such situation, he determines that this connection is constituted by the substitution principle, which according to MARSHALL and CASSEL, actuates in the meaning that a production may obtain the less expensive continuation of factors. According to the author, there is specific case of substitution. To set up the optimum substitution points of such means of production sensible to a change of production must be found. Then it is complemented with geographical surface complications, extraeconomic factors and different forms of in diverse branches of economic activities.