Having acknowledged the imperfections to which money made of gold and silver is liable as a measure of value, from the greater or less quantity of labour which may, under varying circumstances, be necessary for the production of those metals, we may be permitted to make the supposition that all these imperfections were removed, and that equal quantities of labour could at all times obtain, from that mine which paid no rent, equal quantities of gold. Gold would then be an invariable measure of value. The quantity indeed would enlarge with the demand, but its value would be invariable, and it would be eminently well calculated to measure the varying value of all other things. I have already in a former part of this work considered gold as endowed with this uniformity, and in the following chapter I shall continue the supposition. In speaking therefore of varying price, the variation will be always considered as being in the commodity, and never in the medium in which it is estimated. CHAPTER IV. ON NATURAL AND MARKET PRICE. In making labour the foundation of the value of commodities, and the comparative quantity of labour which is necessary to their production, the rule which determines the respective quantities of goods which shall be given in exchange for each other, we must not be supposed to deny the accidental and temporary deviations of the actual or market price of commodities from this, their primary and natural price. In the ordinary course of events, there is no commodity which continues for any length of time to be supplied precisely in that decree of abundance, which the wants and wishes of mankind require, and therefore there is none which is not subject to accidental and temporary variations of price. It is only in consequence of such variations, that capital is apportioned precisely, in the requisite abundance and no more, to the production of the different commodities which happen to be in demand. With the rise or fall of price, profits are elevated above, or depressed below their general level, and capital is either encouraged to enter into, or is warned to depart from the particular employment in which the variation has taken place.