Hence, we may understand the decisive importance of the transformation of value and price of labour- power into the form of wages, or into the value and price of labour itself. This phenomenal form, which makes the actual relation invisible, and, indeed, shows the direct opposite of that relation, forms the basis of all the juridical notions of both labourer and capitalist, of all the mystifications of the capitalistic mode of production, of all its illusions as to liberty, of all the apologetic shifts of the vulgar economists.

If history took a long time to get at the bottom of the mystery of wages, nothing, on the other hand, is more easy to understand than the necessity, the raison d' etre, of this phenomenon.

The exchange between capital and labour at first presents itself to the mind in the same guise as the buying and selling of all other commodities. The buyer gives a certain sum of money, the seller an article of a nature different from money. The jurist's consciousness recognizes in this, at most, a material difference, expressed in the juridically equivalent formula: "Do ut des, do ut facias, facio ut des, facio ut facias."⁹

Furthermore, exchange-value and use-value, being intrinsically incommensurable magnitudes, the expressions "value of labour," "price of labour," do not seem more irrational than the expressions "value of cotton," "price of cotton." Moreover, the labourer is paid after he has given his labour. In its function of means of payment, money realizes subsequently the value or price of the article supplied-i.e., in this particular case, the value or price of the labour supplied. Finally, the use-value supplied by the labourer to the capitalist is not, in fact, his labour-power, but its function, some definite useful labour, the work of tailoring, shoemaking, spinning, &tc. That this same labour is, on the other hand, the universal value-creating element, and thus possesses a property by which it differs from all other commodities, is beyond the cognizance of the ordinary mind.

Let us put ourselves in the place of the labourer who receives for 12 hours' labour, say the value produced by 6 hours' labour, say 3s. For him, in fact, his 12 hours' labour is the means of buying the 3s. The value of his labour-power may vary, with the value of his usual means of subsistence, from 3 to 4 shillings, or from 3 to 2 shillings; or, if the value of his labour-power remains constant, its price may, in consequence of changing relations of demand and supply, rise to 4s. or fall to 2s. He always gives 12 hours of labour. Every change in the amount of the equivalent that he receives appears to him, therefore, necessarily as a change in the value or price of his 12 hours' work. This circumstance misled Adam Smith, who treated the working-day as a constant quantity,¹⁰ to the assertion that the value of labour is constant, although the value of the means of subsistence may vary, and the same working-day, therefore, may represent itself in more or less money for the labourer.

Let us consider, on the other hand, the capitalist. He wishes to receive as much labour as possible for as little money as possible. Practically, therefore, the only thing that interests him is the difference between the price of labour-power and the value which its function creates. But, then, he tries to buy all commodities as cheaply as possible, and always accounts for his profit by simple cheating, by buying under, and selling over the value. Hence, he never comes to see that, if such a thing as the value of labour really existed, and he really paid this value, no capital would exist, his money would not be turned into capital.

Moreover, the actual movement of wages presents phenomena which seem to prove that not the value of labour-power is paid, but the value of its function, of labour itself. We may reduce these phenomena to two great classes: 1.) Change of wages with the changing length of the working-day. One might as well conclude that not the value of a machine is paid, but that of its working, because it costs more to hire a machine for a week than for a day. 2.) The individual difference in the wages of different labourers who do the same kind of work. We find this individual difference, but are not deceived by it, in the system of slavery, where, frankly and openly, without any circumlocution, labour-power itself is sold. Only, in the slave system, the advantage of a labour-power above the average, and the disadvantage of a labour- power below the average, affects the slave-owner; in the wage-labour system, it affects the labourer himself, because his labour-power is, in the one case, sold by himself, in the other, by a third person.