(Các tiện ích cận biên của hàng hoá để Jones và Smith, tất nhiên, không thể so sánh, kể từ khi họ không có thể được đo, và việc hai quy mô giá trị không thể được giảm một trong biện pháp hoặc quy mô.) Tuy nhiên, như Jones tiếp tục để trao đổi với Smith đơn vị của X cho các đơn vị Y, | Direct Exchange 87 to Smith the marginal utility of the added unit of X must be greater than the marginal utility of the unit of Y given up. Thus Jones 1 Unit of X Smith occurs if ---------- 1 Unit ofK to Jones . of Addition of Y . of X. to Smith . of Addition of x . of Y. The marginal utilities of the goods to Jones and to Smith are of course not comparable since they cannot be measured and the two value scales cannot be reduced to one measure or scale. However as Jones continues to exchange with Smith units of X for units of Y the marginal utility of X to Jones increases because of the law of marginal utility. Furthermore the marginal utility of the added unit of Y continues to decrease as Jones stock of Y increases because of the operation of this law. Eventually therefore Jones will reach a point where in any further exchange of X for Y the marginal utility of X will be greater than the marginal utility of the added unit of Y so that he will make no further exchange. Furthermore Smith is in a similar position. As he continues to exchange Y for X for him the marginal utility of Y increases and the marginal utility of the added unit of X decreases with the operation of the law of marginal utility. He too will eventually reach a point where a further exchange will lower rather than raise his position on his value scale so that he will decline to make any further exchange. Since it takes two to make a bargain Jones and Smith will exchange units of X for units of Y until one of them reaches a point beyond which further exchange will lead to loss rather than profit. Thus suppose that Jones begins with a position where his assets stock of goods consist of a supply of five horses and zero cows while Smith begins with assets of five cows and zero horses. How much if any exchanges of one cow for one horse 88 Man Economy and State with Power and Market Exchanges Figure 6. Smith Exchanges Figure 5. JONES will be effected is reflected in the value scales of the
