general principle, now stated, is that demand for commodities determines merely the direction of labour, and the kind of wealth produced, but not the quantity or efficiency of the labour, or the aggregate of wealth. But to this there are two exceptions. First, when labour is supported, but not fully occupied, a new demand for something which it can produce, may stimulate the labour thus supported to increased exertions, of which the result may be an increase of wealth, to the advantage of the labourers themselves and of others. Work which can be done in the spare hours of persons subsisted from some other source, can (as before remarked) be undertaken without withdrawing capital from other occupations, beyond the amount (often very small) required to cover the expense of tools and materials, and even this will often be provided by savings made expressly for the purpose. The reason of our theorem thus failing, the theorem itself fails, and employment of this kind may, by the springing up of a demand for the commodity, be called into existence without depriving labour of an equivalent amount of employment in any other quarter. The demand does not, even in this case, operate on labour any otherwise than through the medium of an existing capital, but it affords an inducement which causes that capital to set in motion a greater amount of labour than it did before.
The second exception, of which I shall speak at length in a subsequent chapter, consists in the known effect of an extension of the market for a commodity, in rendering possible an increased development of the division of labour, and hence a more effective distribution of the productive forces of society. This, like the former, is more an exception in appearance than it is in reality. It is not the money paid by the purchaser, which remunerates the labour; it is the capital of the producer: the demand only determines in what manner that capital shall be employed, and what kind of labour it shall remunerate; but if it determines that the commodity shall be produced on a large scale, it enables the same capital to
