Let us suppose that the heights of men in different countries were extremely different, varying from six feet to six inches, and that the trees, shrubs, houses, utensils, and every other product or article were all in proportion, and that the foot-rule in each country bore the same relation to the race of human beings which inhabited it as the English foot-rule does to Englishmen: then, though it is obvious that the length of ten feet in one nation might extend over a much larger portion of space than ten feet in another nation; yet the foot of each nation would measure with accuracy the relative estimation in which men and things were held in regard to height, length, breadth, &c. It would determine whether a man was tall or short in the estimation of his fellow-citizens; whether his shoulders were broad or narrow; whether his circumference was great or small; and not only whether Mr. Pike’s nose was longer than Mr. Chub’s, but whether it was not, in the accustomed language of the country, absolutely a long nose, although perhaps it might not extend to a quarter of an English inch. On the other hand, if, instead of referring to the measure of each country, we were to refer always to an English foot, though we should be able to ascertain the relative portions of space which all the men to whom we applied our measure occupied, we should make sad havoc with the estimates which they and their countrymen had formed of their own heights, and many certainly would be considered as very short who had before always been considered as very tall. Now it must be allowed that the value of a commodity, as it changes with place and time, and depends upon the wants and caprices of man and the means of satisfying them, resembles more the estimate of tall or short, broad or narrow, than a portion of space capable of being ascertained by a measure unchangeable by time and place. When we speak of the value of silver in China, we cannot possibly mean the value of an ounce of Chinese silver brought to London, where, if it were pure, it would be precisely of the same value as an ounce of pure silver which had been in London from time immemorial. What alone we can correctly mean is, the estimation in which the ounce of silver is held in China, determined, at the time, by the state of the supply compared with the demand, and ordinarily by the quantity of Chinese labour and profits necessary to produce it; and if this be what we mean by the value of an ounce of silver in China, there can be no doubt that Chinese labour, and Chinese labour alone, can measure it. Even, however, if we mean the relation of an ounce of silver to all the commodities in China in succession, it would be impossible practically to form any approximation towards a just notion of the result, except by referring the silver to Chinese labour.