Again, in other cases where the higher wages of American workers are accompanied by an equivalent, or more than equivalent, increase of product, that increased product is not due entirely or chiefly to greater intensity or efficiency of labour, but to the use of more highly elaborated labour-saving machinery. The difference between the labour-cost of making and maintaining this improved machinery, and that of making and maintaining the inferior machinery it has displaced, ought clearly to be added in, where a comparison is made between the relation of net labour-cost to product in different countries, or in different stages of industrial development in the same country. The omission of this invalidates much of the reasoning of Schulze-Gaevernitz, Brentano, Rae, and other prophets of "the economy of high wages." The direct labour-cost of each commodity may be as little, or even less, than in England, but the total cost of production[231] and the selling price may be higher. Lastly, in that comparison between England and America, which is in many respects the most serviceable, because the two countries are nearest in their development of industrial methods as well as in the character of their labourers, the difference of money and of real wage is not commonly accompanied by a difference in hours of labour. The evidence we possess does not warrant any universal or even general application of the theory of the economy of high wages. If it was generally true that by increasing wages and by shortening working hours the daily product of each labourer could be increased or even maintained, the social problem, so far as it relates to the alleviation of the poverty and misery of the lower grades of workers, would admit of an easy solution. But though it will be generally admitted that a rise of wages or of the general standard of comfort of most classes of workers will be followed by increased efficiency of labour, and that a shortening of hours will not be followed by a corresponding diminution in output, it by no means follows that it will be profitable to increase wages and shorten hours indefinitely. Just as it is admitted that the result of an equal shortening of hours will be different in every trade, so will the result of a given rise in standard of comfort be different. In some cases highly-paid labour and short hours will pay, in other cases cheaper labour and longer hours. It is not possible by dwelling upon the concomitance of high wages and good work, low wages and bad work, in many of the most highly-developed industries to appeal to the enlightened self-interest of employers for the adoption of a general rise in wages and a general shortening of hours. Because the most profitable business may often be conducted on a system which involves high wages for short intense work with highly evolved machinery, it by no means follows that other businesses may not be more profitably conducted by employing low-paid