money, and the same volume of transactions, the level of prices is ten times as great as before, and the reason is that every piece of money is used ten times instead of once." Whence he concludes: "The effect on prices must be the same when, in effecting transactions, one piece of money is used ten times as when ten pieces of money are used once."[109] Ricardo, too, expresses the dodo-bone theory very explicitly. "If the state charges a seigniorage for coinage, the coined piece will generally exceed the value of the uncoined piece of metal by the whole seigniorage, because it will require a greater quantity of labour, or, which is the same thing, the value of the produce of a greater quantity of labour, to procure it. "While the state alone coins, there can be no limit to this charge of seigniorage; for, by limiting the quantity of the coin, it can be raised to any conceivable value. It is on this principle that paper money circulates; the whole charge for paper money may be considered a seigniorage. Though it has no intrinsic value, yet, by limiting its quantity, its value is as great as an equal denomination of coin, or of bullion in that coin."[110] Would the dodo-bones circulate? Nicholson chose the illustration to throw into the sharpest relief the absence of any value from a non-monetary employment. Nobody has any use for them as dodo-bones. What economic force is there, then, to make them circulate? Nicholson says nothing about an _agreement_ among the traders, _assigning_ a significance[111] to the dodo-bones, so that they might function in the same way that poker chips do--indeed, any such notion would vitiate his illustration, for he proposes to explain an adjustment of prices by natural economic laws. Why then, will any of the traders give up his valuable commodities for the worthless dodo-bones? Will you say that he will take them, not because he wants them himself, but because he knows that others will take them from him? But why would the others want them? Because they in turn can unload them on still others? But this seems a plain case of the vicious circle. It is, in effect, saying that the dodo-bones will circulate because they will circulate. A will take them because B will take them; B will take them because C will take them, C because ... N will take them; N takes them because A will take them.[112] I do not deny that if the traders used the dodo-bones as counters, agreeing that such dodo-bones should represent some other commodity chosen as a standard of values, that the dodo-bones would circulate. But, in that case, they would be, not primary, self-sustaining money, but merely representative, or token money. And just here let me lay down two general propositions[113] respecting the two main functions of money: to serve as a standard, or common measure, of values, the article chosen must, as such, be valuable. The thing measured must be either a fraction or a multiple of the unit of measurement.