The metamorphoses C — M and M — C are transactions between buyers and sellers; they require time to conclude bargains, the more so as the
 struggle goes on in which each seeks to get the best of the other, and
 it is businessmen who face one another here; and “when Greek meets Greek then comes the tug of war.” [A paraphrase of words from the 17th century tragedy The Rival Queens, or the Death of Alexander the Great by Nathaniel Lee. — Ed.] To effect a change in the state of being costs of time and labour-power, not for the purpose of creating value, however, but in
 order to accomplish the conversion of value from one form into another.
 The mutual attempt to appropriate an extra slice of this value on this
 occasion changes nothing. This labour, increased by the evil designs on
 either side, creates no value, any more than the work performed in a judicial
 proceeding increases the value of the subject matter of the suit. Matters
 stand with this labour — which is a necessary element in the capitalist
 process of production as a whole, including circulation or included by
 it — as they stand, say, with the work of combustion of some substance
 used for the generation of heat. This work of combustion does not generate
 any heat, although it is a necessary element in the process of combustion.
 In order, e.g., to consume coal as fuel, I must combine it with oxygen,
 and for this purpose must transform it from the solid into the gaseous
 state (for in the carbonic acid gas, the result of the combustion, coal
 is in the gaseous state); consequently, I must bring about a physical change
 in the form of its existence or in its state of being. The separation of
 carbon molecules, which are united into a solid mass, and the splitting
 up of these molecules into their separate atoms must precede the new combination,
 and this requires a certain expenditure of energy which thus is not transformed
 into heat but taken from it. Therefore, if the owners of the commodities
 are not capitalists but independent direct producers, the time employed
 in buying and selling is a diminution of their labour-time, and for this
 reason such transactions used to be deferred (in ancient and medieval times)
 to holidays.