Question Third. What is the quantity of the store in relation to the Currency? We have seen that the real worth of the currency, so far as dependent on its relation to the magnitude of the store, may vary within certain limits, without affecting its worth in exchange. The diminution or increase of the represented wealth may be unperceived, and the currency may be taken either for more or less than it is truly worth. Usually, it is taken for more; and its power in exchange, or credit-power, is thus increased (or retained) up to a given strain upon its relation to existing wealth. This credit-power is of chief importance in the thoughts, because most sharply present to the experience, of a mercantile community; but the conditions of its stability[78] and all other relations of the currency to the material store are entirely simple in principle, if not in action. Far other than simple are the relations of the currency to that "available labour" which by our definition (p. 219) it also represents. For this relation is involved not only with that of the magnitude of the store to the number, but with that of the magnitude of the store to the mind, of the population. Its proportion to their number, and the resulting worth of currency, are calculable; but its proportion to their will for labour is not. The worth of the piece of money which claims a given quantity of the store, is, in exchange, less or greater according to the facility of obtaining the same quantity of the same thing without having recourse to the store. In other words, it depends on the immediate Cost and Price of the thing. We must now, therefore, complete the definition of these terms. [78] These are nearly all briefly represented by the image used for the force of money by Dante, of mast and sail,-- "Quali dal vento be gonfiate vele Caggiono avvolte, poi che l'alber fiacca Tal cadde a terra la fiera crudele." The image may be followed out, like all of Dante's, into as close detail as the reader chooses. Thus the stress of the sail must be proportioned to the strength of mast, and it is only in unforeseen danger that a skilful seaman ever carries all the canvas his spars will bear: states of mercantile languor are like the flap of the sail in a calm,--of mercantile precaution, like taking in reefs; and the mercantile ruin is instant on the breaking of the mast. All cost and price are counted in Labour. We must know first, therefore, what is to be counted as Labour.