when ambiguity is to be apprehended, to express the idea by the circumlocution which alone conveys it adequately, namely, the average number of purchases made by each piece in order to effect a given pecuniary amount of transactions.
§ 4.The proposition which we have laid down respecting the dependence of general prices upon the quantity of money in circulation, must be understood as applying only to a state of things in which money, that is, gold or silver, is the exclusive instrument of exchange, and actually passes from hand to hand at every purchase, credit in any of its shapes being unknown. When credit comes into play as a means of purchasing, distinct from money in hand, we shall hereafter find that the connexion between prices and the amount of the circulating medium is much less direct and intimate, and that such connexion as does exist, no longer admits of so simple a mode of expression. But on a subject so full of complexity as that of currency and prices, it is necessary to lay the foundation of our theory in a thorough understanding of the most simple cases, which we shall always find lying as a groundwork or substratum under those which arise in practice. That an increase of the quantity of money raises prices, and a diminution lowers them, is the most elementary proposition in the theory of currency, and without it we should have no key to any of the others. In any state of things, however, except the simple and primitive one which we have supposed, the proposition is only true other things being the same: and what those other things are, which must be the same, we are not yet ready to pronounce. We can, however, point out, even now, one or two of the cautions with which the principle must be guarded in attempting to make use of it for the practical explanation of phenomena; cautions the more indispensable, as the doctrine, though a scientific truth, has of late years been the foundation of a greater mass of false theory, and erroneous interpretation of
