OF LABOUR. 49 the labourer receives. This quantity of silver expresses the value of his labour, in the same way that a certain quantity of silver expresses the value of a yard of cloth. Now the quan- tity of ‘silver by which the value of a yard of cloth is expressed, we term the price of the cloth, and, in a manner strictly analogous, the quantity of silver by which the value of a day’s labour is expressed, we term the wages of la- bour. The price of cloth and the wages of labour are so far exactly correspondent expressions. But when I speak of the price of cloth as the subject of causation or change, I do not intend the silver itself. The price of the cloth may be twenty shillings, but what causes the price is not what causes that quantity of silver. To consider the price as being or consisting in the actual silver itself, is an error of the same kind as to consider the length of a piece of timber as consisting in the instrument which we em- ploy to measureit. Were to speak of the real value of the price of cloth, or of the labour and capital employed in producing the price of