Tiện ích cận biên của X để tăng Jones, bởi vì luật pháp của tiện ích cận biên. Hơn nữa, tiện ích cận biên của đơn vị tăng thêm của Y tiếp tục giảm như chứng khoán Jones tăng Y, vì những hoạt động của luật này. | Prices and Consumption 237 good was in a regime of barter. In barter every good had only its ruling market price in terms of every other good fish-price of eggs horse-price of movies etc. In a money economy every good except money now has one market price in terms of money. Money on the other hand still has an almost infinite array of goods-prices that establish the goods-price of money. The entire array considered together yields us the general goods-price of money. For if we consider the whole array of goods-prices we know what one ounce of money will buy in terms of any desired combination of goods . we know what that ounce s worth of money which figures so largely in consumers decisions will be. Alternatively we may say that the money price of any good discloses what its purchasing power on the market will be. Suppose a man possesses 200 barrels of fish. He estimates that the ruling market price for fish is six ounces per 100 barrels and that therefore he can sell the 200 barrels for 12 ounces. The purchasing power of 100 barrels on the market is six ounces of money. Similarly the purchasing power of a horse may be five ounces etc. The purchasing power of a stock of any good is equal to the amount of money it can buy on the market and is therefore directly determined by the money price that it can obtain. As a matter of fact the purchasing power of a unit of any quantity of a good is equal to its money price. If the market money price of a dozen eggs the unit is 1 8 ounce of gold then the purchasing power of the dozen eggs is also 1 8 of an ounce. Similarly the purchasing power of a horse above was five ounces of an hour of X s labor three ounces etc. For every good except money then the purchasing power of its unit is identical to the money price that it can obtain on the market. What is the purchasing power of the monetary unit Obviously the purchasing power of . an ounce of gold can be considered only in relation to all the goods that the ounce could .
