One consequence of the peculiar nature of labour-power as a commodity
 is, that its use-value does not, on the conclusion of the contract between
 the buyer and seller, immediately pass into the hands of the former. Its
 value, like that of every other commodity, is already fixed before it goes
 into circulation, since a definite quantity of social labour has been spent
 upon it; but its use-value consists in the subsequent exercise of its force.
 The alienation of labour-power and its actual appropriation by the buyer,
 its employment as a use-value, are separated by an interval of time. But
 in those cases in which the formal alienation by sale of the use-value
 of a commodity, is not simultaneous with its actual delivery to the buyer,
 the money of the latter usually functions as means of payment. [12]
 In every country in which the capitalist mode of production reigns, it
 is the custom not to pay for labour-power before it has been exercised
 for the period fixed by the contract, as for example, the end of each week.
 In all cases, therefore, the use-value of the labour-power is advanced
 to the capitalist: the labourer allows the buyer to consume it before he
 receives payment of the price; he everywhere gives credit to the capitalist.
 That this credit is no mere fiction, is shown not only by the occasional
 loss of wages on the bankruptcy 171of the capitalist, [13]
 but also by a series of more enduring consequences. [14]
 Nevertheless, whether money serves as a means of purchase or as a means
 of payment, this makes no alteration in the nature of the exchange of commodities.
 The price of the labour-power is fixed by the contract, although it is
 not realised till later, like the rent of a house. The labour-power is
 sold, although it is only paid for at a later period. It will, therefore,
 be useful, for a clear comprehension of the relation of the parties, to
 assume provisionally, that the possessor of labour-power, on the occasion
 of each sale, immediately receives the price stipulated to be paid for
 it.