“There are two parts to the problem of measuring the objective exchange-value of money. First we have to obtain numerical demonstration of the fact of variations in the objective exchange-value of money; then the question must be decided whether it is possible to make a quantitative examination of the causes of particular price movements, with special reference to the question whether it would be possible to produce.So far as the first-named problem is concerned, it is self-evident that its solution must assume the existence of a good, or complex of goods, of unchanging objective exchange-value. The fact that such goods are inconceivable needs no further elucidation.If the one is proved to be soluble, then so also is the other; and proof of the insolubility of the one is also proof of the insolubility of the other.”