Under certain assumptions, an increase or decrease in the quantity either of the metallic money in circulation, or of the tokens of value in circulation seems to affect _uniformly_ the prices of commodities. With each fall or rise of the _value_ of gold or silver in which the exchange values of commodities are estimated as prices, there is a rise or fall of prices, because of the change in their measure of value; as a result of the rise or fall of prices, a greater or smaller quantity of gold and silver is circulating as coin. But the apparent phenomenon is the fall in prices―the exchange value of commodities remaining the same―accompanied by an increased or diminished quantity of the medium of circulation. On the other hand, if the quantity of tokens of value rises above or falls below its required level, it is forcibly reduced to the latter by a fall or rise of prices. In either case the same effect seems to be brought about by the same cause, and Hume holds fast to this semblance. Every scientific inquiry into the relation between the volume of the circulating medium and the movement of prices must assume the value of the money material as given. Hume, on the contrary, considers exclusively periods of revolution in the value of the precious metals, i. e. revolutions in the measure of value. The rise of prices which occurred simultaneously with the increase of metallic money after the discovery of the American mines forms the historical background of his theory, while his polemic against the monetary and mercantile system furnishes its practical motive. The importation of precious metals can naturally increase while their cost of production remains the same. On the other hand, a decrease in their value, i. e. in the labor-time required for their production will reveal itself first of all in their increased imports. Hence, said the later followers of Hume, a decrease in the value of the precious metals, reveals itself in an increased volume of the circulating medium, and the increased volume of the latter is shown in the rise of prices. As a matter of fact, however, the rise in price affects only exported commodities, which are exchanged for gold and silver as commodities and not as mediums of circulation. Thus, the prices of these commodities, which are now estimated in gold and silver of lower value, rise as compared with the prices of all other commodities whose exchange value continues to be estimated in gold or silver according to the standard of their old cost of production. This twofold appraisement of the exchange values of commodities in the same country can naturally be only temporary, and the gold and silver prices must become equalized in the proportions determined by the exchange values themselves, so that finally the exchange values of all commodities come to be estimated according to the new value of the money material. The development of this process, as well as the ways and means in which the exchange value