Protection, according to Carey, by furnishing a ready market for agricultural products, would free agriculture from the burden of an exorbitant cost of carriage to a distant place. This argument, which List[604] merely threw out as a passing suggestion, continually recurs with the American author. But, as Stuart Mill justly remarked,[605] if America consents to such expenditure it affords a proof that she procures by means of international exchange more manufactured goods than if she manufactured them herself. Another no less debatable point: The exportation of agricultural products, says Carey, exhausts the soil, for the products being consumed away from the spot where they are grown, the fertilizing agents which they contain are not restored to the earth; a manufacturing population in the immediate neighbourhood[606] would remedy this. But, as John Stuart Mill again remarks,[607] and justly enough, it is not Free Trade that forces America to export cereals. If she does so, it is because exhaustion of soil appears to her an insignificant inconvenience compared with the advantage gained by exportation. Carey, finally, was one of the first to discover in Protection a means of increasing wages. Once the complex economic State is established there arises a keen competition between the _entrepreneurs_ who require the service of labour—a competition which naturally benefits the workman. But this advantage, granting that it does exist, is more than counterbalanced by the increased price of goods. We see that Carey, although sharing the fundamental conceptions of List, employs arguments that are much less valid. Both in power of exposition and in the scientific value of his work, the German author shows himself vastly superior to his American successor. He is also much more moderate. Carey is not content with industrial Protection; he demands agricultural Protection as well, and the duties, though a little higher than those proposed by List, seem hardly sufficient for him. Despite all this similarity of views, Carey does not owe his inspiration to List. He was acquainted with the _National System_ and he quoted it. But American economic literature had already supplied him with analogous suggestions. Even more than books, the economic life of America itself as it evolved before his very eyes had contributed to the formation of his ideas. It was the progress of America under a Protective _régime_, it was the spectacle of a country as yet entirely new and sparsely populated, increasing the produce of her soil as colonisation extended, and multiplying her wealth as population became more dense, that inspired him with the idea of a policy of isolation with a view to hastening the utilisation of those enormous resources. More fortunate than List, he saw his ideas accepted, if not by the scientific experts of his country (who on the whole remained aloof), at least by the American politician, who has applied his principles rather freely.[608]