was diametrically opposed to Ricardo's law of diminishing returns. His proof was an historical one, that in fact the poorer, not the richer lands, were first taken into cultivation. This, however, did not explain the fact that different grades of [pg 040] land are simultaneously under cultivation, on which Ricardo's doctrine of rent is based. The constantly increasing production of land naturally led Carey to believe in the indefinite increase of population. He, however, was logically brought to accept the supposed law of an ultimate limit to numbers suggested by Herbert Spencer, based on a diminution of human fertility. He tried to identify physical and social laws, and fused his political economy in a system of “Social Science” (1853), and his “Unity of Law” (1872). From about 1845 he became a protectionist, and his writings were vigorously controversial. In his doctrines on money he is distinctly a mercantilist;94 but, by his earnest attacks on all that has been gained in the science up to his day, he has done a great service in stimulating inquiry and causing a better statement of results. While undoubtedly the best known of American writers, yet, because of a prolix style and an illogical habit of mind, he has had no extended influence on his countrymen.95
The effect of the civil war is now beginning to show itself in an unmistakable drift toward the investigation of economic questions, and there is a distinctly energetic tone which may bring new contributions from American writers. General