of national wealth, and to demonstrate the most effectual plan of advancing a people to greatness," he is correct in indicating that Smith's strong point lies in the extensive field of historical illustration, which he makes use of in the course of his book. In the appeal to nature he was only following previous writers, and also in his conception of nature he cannot claim originality. Petty, like Smith, professedly dealing solely with social phenomena, approaches his work with the same optimistic conception of nature, and uses the test of obedience to natural laws with a like confidence. Taking the first book of the "Wealth of Nations," we can see that a large portion of its contents can be found in an undeveloped form in Petty's writings. This statement certainly holds good with regard to division of labor and the principle that occasions it, to price, to the rent of land. The three sources of national wealth are in one of Petty's tracts, the "Verbum Sapienti," distinguished with precision. Petty lays stress upon the distinction as being a valuable basis for improved taxation. It did not enter within his purpose to give this principle a wider application. Whatever Petty has said on the subject of money is so accurate and so penetrating that it is of great permanent value. Smith or any other writer can only follow in his footsteps, and repeat what he has already said in his clear and luminous treatment of currency in the "Anatomy of Ireland," in the "Treatise on Taxes and Contributions," and elsewhere. It is curious that Smith when he takes up interest approximates
