Page 45: “If one coat represents x days’ labour, two coats represent 2x days’ labour, and so on. But assume that the duration of the labour necessary for the production of a coat becomes doubled or halved. In the first case, one coat is worth as much as two coats were before; in the second case, two coats are only worth as much as one was before, although in both cases one coat renders the same service as before, and the useful labour embodied in it remains of the same quality. But the quantity of labour spent on its production has altered.
“An increase in the quantity of use-values is an increase of material wealth. With two coats, two men can be clothed, with one coat only one man. Nevertheless, an increased quantity of material wealth may correspond to a simultaneous fall in the magnitude of its value. This antagonistic movement has its origin in the two-fold character of labour. Productive power has reference, of course, only to labour of some useful concrete form, the efficacy of any special productive activity during a given time being dependent on its productiveness. Useful labour becomes, therefore, a more or less abundant source of products, in proportion to the rise or fall of its productiveness.”
Here we have an important concept: the productiveness of labor. In other words, in a given society at a given time, how productive is average labor? It is easy to see in a given case: a man driving in nails with a rock is less productive than one using a hammer; and using a power hammer permits him to be even more productive. It is clear, then, that the introduction of the power hammer makes anyone using it more productive (that is, can accomplish more in a given time); it follows that the introduction of the power hammer makes the society more productive, albeit by a trivial amount. Increased productivity means less labor-time spent on a given commodity, which means a lower value, which translates (though we haven’t gotten there yet) to a lower cost.
“The same change in productive power, which increases the fruitfulness of labour, and, in consequence, the quantity of use-values produced by that labour, will diminish the total value of this increased quantity of use-values, provided such change shorten the total labour-time necessary for the production; and vice versa.
Page 46: “On the one hand all labour is, speaking physiologically, an expenditure of human labour-power, and in its character of identical abstract human labour it creates and forms the value of commodities. On the other hand, all labour is the expenditure of human labour-power in a special form and with a definite aim and, and in this, its character of concrete human labour, it produces use-values.”
And here we have an interesting footnote: “In order to prove that labour alone is that all-sufficient and real measure, by which at all times the value of all commodities can be estimated and compared, Adam Smith says, ‘Equal quantities of labour must at all times and in all places have the same value for the labourer. In his normal state of health, strength, and activity, and with the average degree of skill that he may possess, he must always give up the same portion of his rest, his freedom, and his happiness.’ (Wealth of Nations, b1 ch V.) On the one hand, Adam Smith here (but not everywhere) confuses the determination of value by means of the quantity of labour expended in the production of commodities, with the determination of the values of commodities by means of the value of labour, and seeks in consequence to prove that equal quantities of labour have always the same value. On the other hand, he has a presentiment, that labour, so far as it manifests itself in the value of commodities, counts only as expenditure of labour-power, but he treats this expenditure as a mere sacrifice of rest, freedom, and happiness, not as at the same time the normal activity of living beings. But then, he has the modern wage-labourer in his eye.” Engels makes the additional remark: “The English language has the advantage of possessing different words for the two aspects of labour here considered. The labour which creates Use-Value, and counts qualitatively is Work, as distinguished from Labour; that which creates Value and count quantitatively is Labour as distinguished from Work.”