But all considerable variations of market-rate are commonly checked at an earlier point than the one just indicated by variations in the Supply. A sharper Demand carries up the market-rate, and a higher market-rate commonly acts upon Supply to enlarge it, and an increased Supply too checks the rise of market-rate. _Per contra_, a slacker Demand lowers market-rates, and lowered rates often lessen the Supply by the action of holders and speculators,--holders withdrawing their stock for a better market, and speculators buying now when the article is cheap to store away until it shall be dearer. Thus rise of market-rate from Demand growing stronger is checked doubly; first, by curtailing the number of would-be buyers, and second, by enlarging the Supply: the fall of market-rate from Demand growing weaker is checked doubly; first, by increasing the number of consumers of a now cheaper article, and second, by a diminution of Supply by the action of holders and speculators. This double and harmonious working of the law of the Equalization of Demand and Supply is one of the most comprehensive and beautiful laws in Political Economy. Besides this, we must note the effect on Value of conditions in Supply only, Demand being supposed to continue steady. There are three classes of valuables in respect to the law of their Supply. (1) When the Supply is scant, and cannot be increased at all, as is the case with choice antiques and certain gems and paintings by the old masters, their value may rise to any point under the action of Demand, there is and can be in such cases no market-rate, and the individual value will be struck at the point of equalization of the demand then existing with the supply there offered. For instance, the French Government paid, in 1852, 615,300 francs for a painting by Murillo, which had belonged to Marshal Soult. The genuine Murillos are comparatively few, and their number cannot be increased, and their merit causes a strong "desire" to possess them, and their value rises in connection with the limitation of Supply to a point beyond which no one purchaser can be found. When this painting was offered in Paris for sale, many "persons" of course were anxious to buy it, there was but one painting, there could be but one purchaser, value rose under the influence of a sharp Demand, the rise could not be checked by any duplication of the Supply, and the equation was complete and the value for that sale determined when one party distanced all other competitors and offered a sum greater than any one else would give. The same principle controls all sales of this sort, and is practically the principle of the _Auction_, whose very name indicates its nature in this regard, that Demand becomes restricted to one party, and that the highest bidder.