In this chapter, the dogma-historical (_dogmengeschichtliche_) part is of the utmost importance, because it treats of the connection between the deepest fundamental notions and the principal branches of practical life. It is clear that every political economist must construct his exposition of productiveness on his prior notions of goods and value. We must, therefore, draw a distinction between expositions which are logical but altogether too narrow, and wholly erroneous ones.(311) Thus, the Mercantile System admits every mode of applying the three factors of production, but considers them really productive only in so far as they increase the quantity of the precious metals possessed by the nation, either through the agency of mining at home, or by means of foreign trade. This view stands and falls with the altogether too limited idea of national wealth before mentioned (§ 9), which this system advocated.(312) The majority of the followers of the Mercantile System ascribe more power to industry to attract gold and silver from foreign parts, than to agriculture, and to the finer kinds of industry than to the coarser; to active and direct trade, more than to passive and indirect trade. Section XLIX. Critical History Of The Idea Of Productiveness.—The Doctrine Of The Physiocrates. The doctrine of the Physiocrates is to be explained in part by a very natural reaction from the narrow-heartedness of the Mercantile System, and at the same time, by a presentiment, misunderstood, of the true theory of rent. (§ 150 ff.). Of the six classes of labor mentioned above (§ 38), those only are called productive which increase the quantity of raw material useful for human ends. All the other classes, it matters not how useful, are called sterile, salaried, because they draw their income only from the superabundance of land-owners and the workers of the soil. Tradesmen, in the narrower sense of the term, produce only a change in the form of the material, the higher value of which depends on the quantity of other material consumed for the purposes of the tradesman’s labor. If any of this material is saved, the value of their products sinks, although to the advantage of the economy of the whole nation. In any case, industry could create no wealth, but only make existing wealth more lasting. It might, so to speak, accumulate the value of the quantity of food consumed during the building of a house in the house itself.(313)