From the treatment of the production of surplus-value, so far,
 it follows that not every sum of money, or of value, is at pleasure transformable
 into capital. To effect this transformation, in fact, a certain minimum
 of money or of exchange-value must be presupposed in the hands of the individual
 possessor of money or commodities. The minimum of variable capital is the
 cost price of a single labour-power, employed the whole year through, day
 in, day out, for the production of surplus-value. If this labourer were
 in possession of his own means of production, and were satisfied to live
 as a labourer, he need not work beyond the time necessary for the reproduction
 of his means of subsistence, say 8 hours a day. He would, besides, only
 require the means of production sufficient for 8 working-hours. The capitalist,
 on the other hand, who makes him do, besides these 8 hours, say 4 hours’
 surplus-labour, requires an additional sum of money for furnishing the
 additional means of production. On our supposition, however, he would have
 to employ two labourers in order to live, on the surplus-value appropriated
 daily, as well as, and no better than a labourer, i.e., to be able to satisfy
 his necessary wants. In this case the mere maintenance of life would 292be
 the end of his production, not the increase of wealth; but this latter
 is implied in capitalist production. That he may live only twice as well as an ordinary labourer, and besides turn half of the surplus-value produced
 into capital, he would have to raise, with the number of labourers, the
 minimum of the capital advanced 8 times. Of course he can, like his labourer,
 take to work himself, participate directly in the process of production,
 but he is then only a hybrid between capitalist and labourer, a “small
 master.” A certain stage of capitalist production necessitates that the
 capitalist be able to devote the whole of the time during which he functions
 as a capitalist, i.e., as personified capital, to the appropriation
 and therefore control of the labour of others, and to the selling of the
 products of this labour.[4] The guilds of the middle
 ages therefore tried to prevent by force the transformation of the master
 of a trade into a capitalist, by limiting the number of labourers that
 could be employed by one master within a very small maximum. The possessor
 of money or commodities actually turns into a capitalist in such cases
 only where the minimum sum advanced for production greatly exceeds the
 maximum of the middle ages. Here, as in natural science, is shown the correctness
 of the law discovered by Hegel (in his “Logic”), that merely quantitative
 differences beyond a certain point pass into qualitative changes.[5]