The leap taken by value from the body of the commodity, into the body
 of the gold, is, as I have elsewhere called it, the salto mortale of the
 commodity. If it falls short, then, although the commodity itself is not
 harmed, its owner decidedly is. The social division of labour causes his
 labour to be as one-sided as his wants are many-sided. This is precisely
 the reason why the product of his labour serves him solely as exchange-value.
 But it cannot acquire the properties of a socially recognised universal
 equivalent, except by being converted into money. That money, however,
 is in some one else’s pocket. In order to entice the money out of that
 pocket, our friend’s commodity must, above all things, be a use-value to
 the owner of the money. For this, it is necessary that the labour expended
 upon it, be of a kind that is socially useful, of a kind that constitutes
 a branch of the social division of labour. But division of labour is a
 system of production which has grown up spontaneously and continues to
 grow behind the backs of the producers. The commodity to be exchanged may
 possibly be the product of some new kind of labour, that pretends to satisfy
 newly arisen requirements, or even to give rise itself to new requirements.
 A particular operation, though yesterday, perhaps, forming one out of the
 many operations conducted by one producer in creating a given commodity,
 may to-day separate itself from this connexion, may establish itself as
 an independent branch of labour and send its incomplete product to market
 as an independent commodity. The circumstances may or may not be ripe for
 such a separation. To-day the product satisfies a social want. Tomorrow
 the article may, either altogether or partially, be superseded by some
 other appropriate product. Moreover, although our weaver’s labour may be
 a recognised branch of the social division of labour, yet that fact is
 by no means sufficient to guarantee the utility of his 20 yards of linen.
 If the community’s want of linen, and such a want has a limit like every
 other want, should already be saturated by the products of rival weavers,
 our friend’s product is superfluous, redundant, and consequently
 useless. Although people do not look a gift-horse in the mouth, our friend
 does not frequent the market for the purpose of making presents. But suppose
 his product turn out a real use-value, and thereby attracts money? The
 question arises, how much will it attract? No doubt the answer is already
 anticipated in the price of the article, in the exponent of the magnitude
 of its value. We leave out of consideration here any accidental miscalculation
 of value by our friend, a mistake that is soon rectified in the market.
 We suppose him to have spent on his product only that amount of labour-time
 that is on an average socially necessary. The price then, is merely the
 money-name of the quantity of social labour realised in his commodity. But
 without the leave, and behind the back, of our weaver, the old-fashioned
 mode of weaving undergoes a change. The labour-time that yesterday was
 without doubt socially necessary to the production of a yard of linen,
 ceases to be so to-day, a fact which the owner of the money is only too
 eager to prove from the prices quoted by our friend’s competitors. Unluckily
 for him, weavers are not few and far between. Lastly, suppose that every
 piece of linen in the market contains no more labour-time than is socially
 necessary. In spite of this, all these pieces taken as a whole, may have
 had superfluous labour-time spent upon them. If the market cannot stomach
 the whole quantity at the normal price of 2 shillings a yard, this proves
 that too great a portion of the total labour of the community has been
 expended in the form of weaving. The effect is the same as if each individual
 weaver had expended more labour-time upon his particular product than is
 socially necessary. Here we may say, with the German proverb: caught together,
 hung together. All the linen in the market counts but as one article of
 commerce, of which each piece is only an aliquot part. And as a matter
 of fact, the value also of each single yard is but the materialised form
 of the same definite and socially fixed quantity of homogeneous human labour.
 [17]