carried in the first and second editions of this work. But intelligent criticisms (chiefly those of my friend Mr. William Thornton), and subsequent further investigation, have shown that the doctrine stated in the preceding pages, though correct as far as it goes, is not yet the complete theory of the subject matter.
It has been shown that the exports and imports between the two countries (or, if we suppose more than two, between each country and the world) must in the aggregate pay for each other, and must therefore be exchanged for one another at such values as will be compatible with the equation of international demand. That this, however, does not furnish the complete law of the phenomenon, appears from the following consideration: that several different rates of international value may all equally fulfil the conditions of this law.
The supposition was, that England could produce 10 yards of cloth with the same labour as 15 of linen, and Germany with the same labour as 20 of linen; that a trade was opened between the two countries; that England thenceforth confined her production to cloth, and Germany to linen; and, that if 10 yards of cloth should thenceforth exchange for 17 of linen, England and Germany would exactly supply each other's demand: that, for instance, if England wanted at that price 17,000 yards of linen, Germany would want exactly the 10,000 yards of cloth, which, at that price, England would be required to give for the linen. Under these suppositions it appeared, that 10 cloth for 17 linen, would be, in point of fact, the international values.
But it is quite possible that some other rate, such as 10 cloth for 18 linen, might also fulfil the conditions of the equation of international demand. Suppose that at this last rate, England would want more linen than at the rate of 10 for 17, but not in the ratio of the cheapness; that she would not want the 18,000 which she could now buy with 10,000 yards of cloth, but would be content with 17,500, for which she would pay (at the new rate of 10 for 18) 9722 yards of cloth. Germany, again, having to pay dearer for cloth than
