one-twelfth of the labour of making the plough must be placed to the account of each year's harvest. A twelfth part of the labour of making a plough is an appreciable quantity. But the same set of tools, perhaps, suffice to the ploughmaker for forging a hundred ploughs, which serve during the twelve years of their existence to prepare the soil of as many different farms. A twelve-hundredth part of the labour of making his tools, is as much, therefore, as has been expended in procuring one year's harvest of a single farm: and when this fraction comes to be further apportioned among the various sacks of corn and loaves of bread, it is seen at once that such quantities are not worth taking into the account for any practical purpose connected with the commodity. It is true that if the tool-maker had not laboured, the corn and bread never would have been produced; but they will not be sold a tenth part of a farthing dearer in consideration of his labour.
§ 2.Another of the modes in which labour is indirectly or remotely instrumental to the production of a thing, requires particular notice: namely, when it is employed in producing subsistence, to maintain the labourers while they are engaged in the production. This previous employment of labour is an indispensable condition to every productive operation, on any other than the very smallest scale. Except the labour of the hunter and fisher, there is scarcely any kind of labour to which the returns are immediate. Productive operations require to be continued a certain time, before their fruits are obtained. Unless the labourer, before commencing his work, possesses a store of food, or can obtain access to the stores of some one else, in sufficient quantity to maintain him until the production is completed, he can undertake no labour but such as can be carried on at odd intervals, concurrently with the pursuit of his subsistence. He cannot obtain food itself in any abundance; for every mode of so obtaining it, requires that there be already food in store. Agriculture only brings
