The whole turns upon the possibility of extending the market for gold. A child must see that, if the demand for gold cannot be materially increased, it is altogether nugatory that nature should indefinitely enlarge the supply. In articles that adapt themselves to a variable scale of uses, so as to be capable of substitution for others, according to the relations of price, it is often possible enough that, in the event of any change which may lower their price, the increased demand may go on without assignable limits. For instance, when iron rises immoderately in price, timber is substituted to an indefinite extent. But, on the other hand, where the application is severely circumscribed, no fall of price will avail to extend the demand. Certain herbs, for instance, or minerals, employed for medicinal purposes, and for those only, have their supply regulated by the demand of hospitals and of private medical practitioners. That demand being once exhausted, no cheapness whatever will extend the market. Suppose the European market for leeches to be saturated; every man, suppose, is supplied; in that case, even an _extra_ thousand cannot be sold. The purpose which leeches answer has been met. And after _that_ nobody will take them as a gift. But in the case of gold, it is imagined that, although the market is pretty stationary whilst the price is stationary, let that price materially lower itself, and immediately the substitutions of gold for other metals, or for other decorative materials (as ivory, etc.), would begin to extend; and commensurately with such extensions the regular gold market would widen. This is the prevailing conceit. Now let us consider it.