the people had grown accustomed to it, suffice for all the wants of circulation. But, in commerce with the rest of the world, the greater quantity and greater cheapness of the precious metals, that is of those commodities which are most current and are possessed of the greatest amount of economic energy, must, without fail, be of the greatest advantage to a country; and this irrespective of the fact that they are under certain circumstances the symptom of an especially highly developed public economy. If we suppose two nations, A and B, equal in every other point, but that A has twice as much money as B, and that prices are twice as high there as in B; yet, with the same effort or sacrifice, A could levy twice as many taxes as B. In case of a war between them, A might pay in ready money for the necessities of an army which had invaded B, with one-fourth the sacrifice which B would have to make to support its army in A, if we reverse the case, and suppose that B had invaded A.(771) Chapter IV. History Of Prices. Section CXXVII. Measure Of Prices,—Constant Measure. If we had a measure of prices with the same universality of application and the same unchangeableness as the measure of length, which is determined by astronomical calculation, we should be able, not only to clearly understand all the data relating to value, that is to say, a not unimportant portion of historical science, but we should, moreover, have a practical means to condition and fix even perpetual annuities, in such a way, that they would always afford the same economic and purchasing power to the person receiving them. No wonder, therefore, that political economists since Petty’s time have zealously labored to find a _constant_ measure of prices.(772) If by this we understand a species of goods such that it should always maintain equal exchange-power, as compared with all other commodities, the idea of a “constant” measure of prices is unthinkable. We would have to suppose here, that not a single kind of goods varied in its price; since, otherwise, at least as compared with those that varied in price, the measure of prices would itself be variable.(773) But we may, indeed, search for a kind of goods such that its inherent elements and the elements peculiar to it, so far as it is itself concerned, and which go to determine price, should exert the same uniform influence at all times. If there be such a kind of goods, and its value in exchange as compared with other kinds of goods were to vary, we should be certain, at least, that the cause of the change was not in it, but in them; that _it_ had not grown dearer or cheaper, but that they had grown cheaper or dearer. Such a kind of goods would have these two characteristics: A. A given amount of it would, under all circumstances, have the same value in use for the same number of persons. B. It would