The rate of interest, though ultimately and permanently governed by the rate of profit, is however subject to temporary variations from other causes. With every fluctuation in the quantity and value of money, the prices of commodities naturally vary. They vary also, as we have already shewn, from the alteration in the proportion of supply to demand, although there should not be either greater facility or difficulty of production. When the market prices of goods fall from an abundant supply, from a diminished demand, or from a rise in the value of money, a manufacturer naturally accumulates an unusual quantity of finished goods, being unwilling to sell them at very depressed prices. To meet his ordinary payments, for which he used to depend on the sale of his goods, he now endeavours to borrow on credit, and is often obliged to give an increased rate of interest. This however is but of temporary duration; for either the manufacturer's expectations were well grounded, and the market price of his commodities rises, or he discovers that there is a permanently diminished demand, and he no longer resists the course of affairs: prices fall, and money and interest regain their real value. If by the discovery of a new mine, by the abuses of banking, or by any other cause, the quantity of money be greatly increased, its ultimate effect is to raise the prices of commodities in proportion to the increased quantity of money; but there is probably always an interval, during which some effect is produced on the rate of interest.