It is apparent that the market price of any commodity will be high if that commodity has high utility or if the commodity is relatively scarce, or, on the other hand, if money is plentiful and therefore has low marginal utility. The price of any commodity depends, therefore, upon its relative utility as compared with other commodities and upon the price of other commodities in general, that is, the price level; but the price level is an average ratio between the quantities of goods exchanged and the quantity of money against which they are exchanged. The quantity of money has two elements: the number of units of money, and the number of times that these units are exchanged against goods within a period. Ignoring for the time being the influence of deposit currency, the price level depends upon three factors: (1) the quantity or number of money units in circulation, (2) their velocity of circulation, and (3) the quantity of goods against which they are exchanged. The price level varies directly as the quantity of money and the velocity of circulation and inversely as the volume of goods traded. This is the quantity theory of money. The price level varies with the total purchasing power of the community, and this purchasing power is the product obtained by multiplying the number of dollars in circulation by the number of times the dollars circulate within a period. Or stated inversely, the value of a dollar (its power to command articles in exchange) decreases as the number of dollars or their rate of circulation increases.