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 of relative value like money, the substitution of labour so applied instead of money will give the measure we want.

It remains, therefore, to be considered more particularly how far the labour which a commodity will command appears to be an adequate measure of value in exchange at different periods and in different countries, according to the most usual and correct sense in which the term is practically applied; and it will be recollected that I have endeavoured to show, and I trust with success, that this sense is not the general power of purchasing possessed by a particular commodity, but its power of purchasing arising from intrinsic causes, which includes all the causes, of whatever kind they may be, which have contributed to the limitation of its supply compared with the demand.

Keeping in mind, therefore, the meaning attached to the term value of a commodity at a particular time and place, let us compare the values of two commodities, one of which was produced in the time of Edward III. and the other in the time of William IV.

And first let us suppose, for the sake of clearness, that the common agricultural labour of each period, which may be taken as the standard, is exactly of the same degree of strength, and is employed for the same number of hours, and further, that there are some commodities which, both at these periods and during the whole of the interval between them, are produced by this kind of labour alone, and brought to market immediately.

Perhaps these suppositions have not been very far from the truth in this country since the time of Edward III. I should suppose that the physical strength of the men of that period was nearly the same as at present, and that an ordinary day's work of agricultural labour was nearly of the same length; and it is generally allowed that at all times there are a few commodities produced by labour alone.

It is obvious that commodities so produced would, at any particular period, exchange with one another,