In the critical study which follows, virtually every doctrine and every assumption of this preliminary statement will be challenged. I shall deny, first, that the quantity of goods to be exchanged and the quantity of money to be exchanged for the goods, are independent quantities, maintaining, rather, that an increase in either of them tends normally to be accompanied by an increase in the other. Quantity of goods and quantity of money _exchanged_ are not simple physical stocks, given data. Rather, they are consequences of human choices and human relationships, and vary from a large number of highly complex psychological causes, many of which are common to both. I shall deny, second, that "rapidity of circulation," either of goods or of money, is a simple constant, independent of quantity of goods or of quantity of money. I shall maintain, rather, that rapidity of circulation of money is a phenomenon which calls for psychological explanation: that the rapidity of money really means the _activities of men_; that these activities are complex, and obey no simple law; that instead of being an independent factor, constant, in the situation, the rapidity of circulation of money is bound up with the quantity of money, the quantity of goods to be exchanged, the rapidity of circulation of goods, and the prices of the goods, and that the rapidity of circulation of goods is likewise causally dependent on the factors named--or better, on the causes which control them; that rapidity of circulation, whether of money or of goods, is not a causal factor independent of prices, but rather in part depends on prices. In the third place, I deny the doctrine that the question as to _what_ the money-unit is made of is irrelevant. On the contrary, I shall maintain that the _quality_ of money, rather than its quantity, is the determining factor. I shall not maintain that only money made of or redeemable in valuable bullion can circulate, nor shall I maintain that the value of money depends wholly on the value of its bullion content when money is made of valuable metal. I recognize that value can come from other sources. But I shall maintain that value from some source other than the monetary employment is an essential precondition of the monetary employment, even though recognizing that that monetary employment may, in a way later to be analyzed, add to the original value of the money. The doctrine that only physical quantities, or abstract numbers, of goods are relevant I shall challenge especially, maintaining, on the contrary, that the psychological significances, the values, of goods are the really important thing, so that an increase in the number of one sort of goods may have a very different effect on the average of prices from an increase of the same number of units of some other good, and so that an increase in the number of goods exchanged under one set of conditions may have a very different effect on prices--or may be accompanied by a