The time of production naturally comprises the period of the labour-process, but is not comprised in it. It will be remembered first of all that a part of the constant capital exists in the form of instruments of labour, such as machinery, buildings, etc., which serve the same constantly repeated labour-processes until they are worn out. Periodical interruptions of the labour-process, by night for instance, interrupt the functioning of these instruments of labour, but not their stay at the place of production. They belong to this place when they are in function as well as when they are not. On the other hand the capitalist must have a definite supply of raw material and auxiliary material in readiness, in order that the process of production may take place for a longer or shorter time on a previously determined scale, without being dependent on the accidents of daily supply from the market. This supply of raw material, etc., is productively consumed only by degrees. There is, therefore, a difference between its time of production  and its time of functioning. The time of production of the means of production in general comprises, therefore, 1) the time during which they function as means of production, hence serve in the productive process; 2) the stops during which the process of production, and thus the functioning of the means of production embodied in it, are interrupted; 3) the time during which they are held in readiness as prerequisites of that process, hence already represent productive capital but have not yet entered into the process of production. The difference so far considered has in each case been the difference between the time which the productive capital stays in the sphere of production and that it stays in the process of production. But the process of production may itself be responsible for interruptions of the labour-process, and hence of the labour-time intervals during which the subject of labour is exposed to the action of physical processes without the further intervention of human labour. The process of production, and thus the functioning of the means of production, continue in this case, although the labour-process, and thus the functioning of the means of production as instruments of labour, have been interrupted. This applies, for instance, to the grain, after it has been sown, the wine fermenting in the cellar, the labour-material of many factories, such as tanneries, where the material is exposed to the action of chemical processes. The time of production is here longer than the labour-time. The difference between the two consists in an excess of the production time over the labour-time. This excess always arises from the latent existence of productive capital in the sphere of production without functioning in the process of production itself or from its functioning in the productive process without taking part in the labour-process. That part of the latent productive capital is held in readiness only as a requisite for the productive process, such as cotton, coal, etc., in a spinning-mill, acts as a creator of neither products nor value. It is fallow capital, although its fallowness is essential for the uninterrupted flow of the process of production. The buildings, apparatus, etc., necessary for the storage of the productive supply (latent capital) are conditions of the productive process and therefore constitute component parts of the advanced productive capital. They perform their function as conservators of the productive components in the preliminary stage. Inasmuch as labour-processes are necessary in this stage, they add to the cost of raw material, etc., but are productive labour and productive surplus-value, because a part of this labour, like of all other wage-labour, is not paid for. The normal interruptions of the entire process of production, the intermissions during which the productive capital does not function, create neither value nor surplus-value. Hence the desire to the work going at night, too. (Buch I, Kap. VIII, 4.) [English edition: Ch. X, 4. Ed.] The intervals in the labour-time which the subject of labour must endure in the process of production itself create neither value nor surplus-value. But they advance the product, form a part of its life, a process through which it must pass. The value of the apparatus, etc., is transferred to the product in proportion to the entire time during which they perform their function; the product is brought to this stage by labour itself, and the employment of these apparatus is as much a condition of production as is the reduction to dust of a part of the cotton which does not enter into the product but nevertheless transfers its value to the product. The other part of the latent capital, such as buildings, machinery, etc., the instruments of labour whose functioning is interrupted only by the regular pauses of the productive process irregular interruptions caused by the restriction of production, crises, etc., are total losses adds value without entering into the creation of the product. The total value which this part of capital adds to the product is determined by its average durability; it loses value, because it loses its use-value, both during the time that it performs its functions as well as during that in which it does not. Finally the value of the constant part of capital, which continues in the productive process although the labour-process is interrupted, re-appears in the result of the productive process. Labour itself has here placed the means of production in conditions under which they pass of themselves through certain natural processes, the result of which is a definite useful effect or a change in the form of their use-value. Labour always transfers the value of the means of production to the product, in so far as it really consumes them in a suitable manner, as means of production. And it does not change the matter whether labour has to bear continually on its subject by means of the instruments of labour in order to produce this effect or whether it merely needs to give the first impulse by providing the means of production with conditions under which they undergo the intended alteration of themselves, in consequence of natural processes, without the further assistance of labour. Whatever may be the reason for the excess of production time over the labour-time whether the circumstance that means of production constitute only latent productive capital and hence are still in a stage preliminary to the actual productive process or that their own functioning is interrupted within the process of production by its pauses or finally that the process of production itself necessitates interruptions of the labour-process in none of these cases do the means of production function as absorbers of labour. And if they do not absorb labour, they do not absorb surplus-labour, either. Hence there is no expansion of the value of productive capital so long as it stays in that part of its production time which exceeds the labour-time, no matter how inseparable from these pauses the carrying on of the process of self-expansion may be. It is plain that the more the production time and labour-time cover each other the greater is the productivity and self-expansion of a given productive capital in a given space of time. Hence the tendency of the capitalist production to reduce the excess of the production time over the labour-time as much as possible. But while the time of production of a certain capital may differ from its labour-time, it always comprises the latter, and this excess is itself a condition of the process of production. The time of production, then, is always that time in which a capital produces use-values and expands, hence functions as productive capital, although it includes time in which it is either latent or produces without expanding its value. Within the sphere of circulation, capital abides as commodity-capital and money-capital. Its two processes of circulation consist in its transformation from the commodity-form into that of money and from the money-form into that of commodities. The circumstance that the transformation of commodities into money is here at the same time a realisation of the surplus-value embodied in the commodities, and that the transformation of money into commodities is at the same time a conversion or reconversion of capital-value into the form of its elements of production does not in the least alter the fact that these processes, as processes of circulation, are processes of the simple metamorphosis of commodities. Time of circulation and time of production mutually exclude each other. During its time of circulation capital does not perform the functions of productive capital and therefore produces neither commodities nor surplus-value. If we study the circuit in its simplest form, as when the entire capital-value passes in one bulk from one phase into another, it becomes palpably evident that the process of production and therefore also the self-expansion of capital-value are interrupted so long as its time of circulation lasts, and that the renewal of the process of production will proceed at a faster or a slower pace depending on the length of the circulation time. But if on the contrary the various parts of capital pass through the circuit one after another, so that the circuit of the entire capital-value is accomplished successively in the circuits of its various component parts, then it is evident that the longer its aliquot parts stay in the sphere of circulation the smaller must be the part functioning in the sphere of production. The expansion and contraction of the time of circulation operate therefore as negative limits to the contraction or expansion of the time of production or of the extent to which a capital of a given size functions as productive capital. The more the metamorphoses of circulation of a certain capital are only ideal, i.e., the more the time of circulation is equal to zero, or approaches zero, the more does capital function, the more does its productivity and the self-expansion of its value increase. For instance, if a capitalist executes an order by the terms of which he receives payment on delivery of the product, and if this payment is made in his own means of production, the time of circulation approaches zero. A capital s time of circulation therefore limits, generally speaking, its time of production and hence its process of generating surplus-value. And it limits this process in proportion to its own duration. This duration may considerably increase or decrease and hence may restrict capital s time of production in a widely varying degree. But Political Economy sees only what is apparent, namely the effect of the time of circulation on capital s process of the creation of surplus-value in general. It takes this negative effect for a positive one, because its consequences are positive. It clings the more tightly to this appearance since it seems to furnish proof that capital possesses a mystic source of self-expansion independent of its process of production and hence of the exploitation of labour, a spring which flows to it from the sphere of circulation. We shall see later that even scientific Political Economy has been deceived by this appearance of things. Various phenomena, it will turn out, give color to this semblance: 1) The capitalist method of calculating profit, in which the negative cause figures a positive one, since with capitals in different spheres of investment, where only the time of circulation are different, a longer time of circulation tends to bring about an increase in prices, in short, serves as one of the causes of equalising profits. 2) The time of circulation is but a phase of the time of turnover; the latter however includes the time of production or reproduction. What is really due to the latter seems to be due to the time of circulation. 3) The conversion of commodities into variable capital (wages) is necessitated by their previous conversion into money. In the accumulation of capital, the conversion into additional variable capital therefore takes place in the sphere of circulation, or during the time of circulation. Consequently it seems that the accumulation thus achieved is owed to the latter. Within the sphere of circulation capital passes through the two antithetical phases C M and M C; it is immaterial in what order. Hence its time of circulation is likewise divided into two parts, viz.: the time it requires for its conversion from commodities into money, and that which it requires for its conversion from money into commodities. We have already learned from the analysis of simple circulation of commodities (Buch I, Kap. III) [English edition: Ch. III. Ed.] that C M, the sale, is the most difficult part of its metamorphosis and that therefore under ordinary conditions it takes up the greater part of its time of circulation. As money, value exists in its always convertible form. As a commodity it must first be transformed into money before it can assume this form of direct convertibility and hence of constant readiness for action. However, in capital s process of circulation, its phase M C has to do with its transformation into commodities which constitute definite elements of productive capital in a given enterprise. The means of production may not be available in the market and must first be produced or they must be procured from distant markets or their ordinary supply has become irregular or prices have changed, etc., in short there are a multitude of circumstances which are not noticeable in the simple change of form M C, but which nevertheless requires now more, now less time also for this part of the circulation phase. C M and M C may be separate not only in time but also in space; the market for buying and the market for selling may be located apart. In the case of factories for instance buyer and seller are frequently different persons. In the production of commodities, circulation is as necessary as production itself, so that circulation agents are just as much needed as production agents. The process of reproduction includes both functions of capital, therefore it includes the necessity of having representatives of these functions, either in the person of the capitalist himself or of wage-labourers, his agents. But this furnishes no ground for confusing the agents of circulation with those of production, any more than it furnishes ground for confusing the functions of commodity-capital and money-capital with those of productive capital. The agents of circulation must be paid by the agents of production. But the capitalists, who sell to and buy from one another, create neither values nor products by these acts, this state of affairs is not changed if they are enabled or compelled by the volume of their business to shift this function on to others. In some businesses the buyers and sellers get paid in the form of percentages on the profits. All talk about their being paid by the consumer does not help matters. The consumers can pay only in so far as they, as agents of production, produce an equivalent in commodities for themselves or appropriate it from production agents either on the basis of some legal title (as their co-partners, etc.) or by personal services. There is a difference between C M and M C which has nothing to do with the difference in forms of commodities and money but arises from the capitalist character of production. Intrinsically both C M and M C are mere conversions of given values from one form into another. But C' M' is at the same time a realisation of the surplus-value contained in C'. M C however is not. Hence selling is more important than buying. Under normal conditions M C is an act necessary for the self-expansion of the value expressed in M, but it is not a realisation of surplus-value; it is the introduction to its production, not an afterword. The form in which a commodity exists, its existence as a use-value, sets definite limits to the circulation of commodity capital C' M'. Use-values are perishable by nature. Hence if they are not productively or individually consumed within a certain time, depending on what they are intended for, in other words, if they are not sold within a certain period, they spoil and lose with their use-value the property of being vehicles of exchange-value. The capital-value contained in them, hence also the surplus-value accrued in it, gets lost. The use-values do not remain the carriers of perennial self-expanding capital-value unless they are constantly renewed and reproduced, are replaced by new use-values of the same or of some other order. The sale of the use-values in the form of commodities, hence their entry into productive or individual consumption effected through this sale is however the ever recurring condition of their reproduction. They must change their old use-form within a definite time in order to continue their existence in a new form. Exchange-value maintains itself only by means of this constant renewal of its body. The use-values of various commodities spoil sooner or later; the interval between their production and consumption may therefore be comparatively long or short; hence they can persist without spoiling in the circulation phase C M for a shorter or longer term in the form of commodity-capital, can endure a shorter or a longer time of circulation as commodities. The limit of the circulation time of a commodity-capital imposed by the spoiling of the body of the commodity is the absolute limit of this part of the time of circulation, or of the time of circulation of commodity-capital as such. The more perishable a commodity and the sooner after its production it must therefore be consumed and hence sold, the more restricted is its capacity for removal from its place of production, the narrower therefore is the spatial sphere of its circulation, the more localised are the markets where it can be sold. For this reason the more perishable a commodity is and the greater the absolute restriction of its time of circulation as commodity on account of its physical properties, the less is it suited to be an object of capitalist production. Such a commodity can come within its grasp only in thickly populated districts or to the extent that improved transportation eliminate distance. But the concentration of the production of any article in the hands of a few and in a populous district may create a relatively large market even for such articles as are the products of large breweries, dairies, etc.
Economic Manuscripts: Capital: Volume Two