buy) as many pairs of shoes as forty hours of social labor will produce.
Generally speaking, a commodity containing ten hours of necessary labor will tend to exchange for gold, or any other commodity containing ten hours of necessary labor.
This is true when price and value are equal. But supply and demand cause commodities to exchange (or sell) above or below their value, temporarily.
A temporary shortage in coal—when the supply does not equal the demand—may enable the dealers to exchange coal above its value for a short time. An over supply of automobiles may cause the manufacturers to offer to sell (or exchange) autos below their value, for a time.
Prices are often a little above or below the value of commodities, but they are always inclining toward the value of commodities.
(Please remember that we are not here speaking of monopoly prices. We shall consider them in a later lesson.)
"If supply and demand equilibrate each other, the market prices of commodities will correspond with their natural prices, that is to say with their values, as determined by the respective quantities of labor required for their production… If, instead of considering only the daily fluctuations, you analyze the movement of market prices for longer periods… you will find that the fluctuations of market prices,
