ber of men, the same time, upon Silver; I say that the neat proceed of the silver is the price of the whole neat proceed of the Corn, and like parts of one the price of like parts of the other... And this also is the way of pitching the true proportion between the values of Gold and Silver, which many times is set but by popular errour. . . This I say to be the foundation of equallizing and ballancing of values; yet in the superstructures and practices hereupon, I confess there is much variety and intricacy; of which hereafter."[1] The promise in these last words is kept by numerous incidental remarks scattered throughout his writings, pointing out how the superstructure differs from what the foundation would lead us to expect, or, in modern language which scarcely misrepresents Petty 's idea, how market price differs from the normal price of his theory. He says, for example, that "forasmuch as almost all Commodities have their Substitutes or Succedanea, and that almost all uses may be answered several wayes; and for that novelty, surprize, example of Superiours, and opinion of unexaminable defects do adde or take away from the price of things, we must adde these contingent Causes to the permanent Causes abovementioned, in the judicious foresight and computation whereof lies the excellency of a Merchant."[2] Compared with anything that preceded it in England,[3] this analysis marks a great theoretical progress. It cuts loose altogether from the mediaeval notion, current at least as late as Hales' Discourse of the Common Weal,[4] that price is arbitrarily determined by the seller, whose exactions must be persistently checked by law. It at least suggests the difference between normal and market price. It clearly enunciates the theory of normal price that dominated economic
