reckoned at about eight years purchase, the species of them is worth as many as land, being in its nature as perpetual for ought we know[1]." The figures to which Petty applies this formula are conjectural, even capricious, but the formula itself is essentially sound, and the ingenious calculation shows that he had a firm grasp upon the problem of capitalization. The various components of the national wealth being thus ascertained, Petty proceeds to use them as a basis for distributing taxation. He holds that, the ratio formalis of riches lying rather in proportion than in quantity, men would be no poorer than now they are should each lose half his estate[2]. Accordingly he proposes various taxes[3] intended to place upon the possessors of each source of income such a proportion of the aggregate burden as the capitalized amounts of their respective incomes may bear to the national wealth which he has calculated.
Petty's interest in the amount of the national wealth thus sprang from his discussion of taxation, and it is clear that traces of its origin hang about it to the end. But he soon came to employ the notion for another purpose also; that is, as a means of comparing England with her commercial rivals, Holland and France. In 1664, Petty had made a "Collection of the Frugalities of Holland[4]," and he repeatedly commended various Dutch practices for adoption in England[5]. Nevertheless, he seems to have considered the current estimate of the Dutch somewhat exaggerated[6], and the conviction apparently grew upon him that it was rather with France than Holland that Englishmen must reckon[7]. In the "Treatise of Taxes" (1662), the Dutch system is held up as a model for English imitation, while no French taxes are mentioned except the gabelle[8], of which he disapproves. In the "Political Arithmetick" (1676) Holland still occupies the first place, but it serves merely as a stalking-horse to disguise the main argument regarding the potential superiority of England to France. In the "Five Essays" (1687) the Netherlands are openly relegated to second place. In making these international comparisons Petty realizes that national wealth is something different from the revenue of the exchequer[9], and is of independent importance to the commonweal. Nevertheless he is unable to divest himself entirely of the cameralistic notions out of which his discussion
