The second principal cause which has prevented labour from being received, according to the language of Adam Smith, as “alone the ultimate and real standard by which the value of all commodities can at all times and places be estimated and compared,”[93] is, that in different periods, and in different countries, it is not really true, as stated by him, that the labourer in working “lays down the same portion of his ease, his liberty, and his happiness.”[94] There is the best reason to believe that the labourer in India, and in many other countries, neither exerts himself so much while he is working, nor works for so many hours a day as an English labourer. A day’s labour, therefore, is not invariable either in regard to intensity or time. But still it appears to me that, for the reasons before stated, that is, because the labour of each place and time measures at that place and time the estimation in which a commodity is held, the state of its supply compared with the demand, the elementary costs of its production, the natural and necessary conditions of the supply, the proportion of the produce to the producers, &c. it must be considered as measuring, with a fair approach towards accuracy, the values of commodities at these places and times, so as to answer the question,—what was the value of broad-cloth of a certain description in the time of Edward III. in England? or, what is the value of money at present in China? The nature of the measure, and the reason why the varying intensity of the labour and the different number of hours employed in the day, do not disqualify it from performing its functions, may perhaps be illustrated by the following comparison:—