As for the difference between M and M', it (m) is simply the money-form of c, the increment of C. M' is composed of M plus m only because C' was composed of C plus c. In C' therefore this difference and the relation of the capital-value to the surplus-value generated by it is present and expressed before both of them are transformed into M', into a sum of money in which both parts of the value come face to face with each other independently and may, therefore, be employed in separate and distinct functions.
M' is only the result of the realisation of C'. Both M' and C'
are merely different forms of self-expanded capital-value, one of them the commodity-form, the other the money-form. Both of them have this in common: that they are self-expanded capital-value. Both of them are materialised capital, because capital-value as such exists here together with the surplus-value, the fruit obtained through it and differing from it, although this relation is expressed only in the irrational form of the relation between two parts of a sum of money or of a commodity-value. But as expressions of capital in relation and contradistinction to the surplus-value produced by it, hence as expressions of self-expanded value, M' and C' are the same and express the same thing, only in different forms. They do not differ as money-capital and commodity-capital but as money and commodities. In so far as they represent self-expanded value, capital acting as capital, they only express the result of the functioning of productive capital, the only function in which capital-value generates value. What they have in common is that both of them, money-capital as well as commodity-capital, are modes of existence of capital. The one is capital in money-form, the other in commodity-form. The specific functions that distinguish them cannot therefore be anything else but differences between the functions of money and of commodities. Commodity-capital, the direct product of the capitalist process of production, is reminiscent of its origin and is therefore more rational and less incomprehensible in form than money-capital, in which every trace of this process has vanished, as in general all special use-forms of commodities disappear in money. It is therefore only when M' itself functions as commodity-capital, when it is the direct product of a productive process instead of being the converted form of this product, that it loses its bizarre form, that is to say, in the production of the money material itself. In the production of gold for instance the formula would be M---C< L MP ... P ... M' (M plus m), where M' would figure as a commodity product, because P furnishes more gold than was advanced for the elements of production of the gold in the first M, the money-capital. In this case the irrational nature of the expression M ... M' (M plus m) disappears. Here a part of a sum of money appears as the mother of another part of the same sum of money.
IV. THE CIRCUIT AS A WHOLE
We have seen that the process of circulation is interrupted at the end of its first phase, M---C< L MP , by P, in which the commodities L and MP bought in the market are consumed as the material and value components of productive capital. The product of this consumption is a new commodity, C', altered in respect of substance and value. The interrupted process of circulation, M---C, must be completed by C---M.
But the bearer of this second and concluding phase of circulation is C', a commodity different in substance and value from the original C. The circulation series therefore appears as 1) M---C 1 ; 2) C' 2 ---M', where in the second phase of the first commodity, C 1 , another commodity of greater value and different use-form, C' 2 , is substituted during the interruption caused by the functioning of P, the production of C' from the elements of C, the forms of existence of productive capital P. However, the first form of appearance in which capital faced us (Buch. I, Kap. IV, 1), [English edition: Ch. IV. -- Ed. ] viz., M---C---M' (extended: 1) M---C 1 ; 2) C 1 ---M') shows the same commodity twice. Both times it is the same commodity into which money is transformed in the first phase and reconverted into more money in the second phase. In spite of this essential difference, both circulations share this much: that in their first phase money is transformed into commodities, and in the second commodities into money, that the money spent in the first phase returns in the second. On the one hand both have in common this reflux of the money to its starting-point, on the other hand also the excess of the returning money over the money advanced. To that extent the formula M---C ... C'---M' is contained in the general formula M---C---M'.
It follows furthermore that each time equally great quantities of simultaneously existing values face and replace each other in the two metamorphoses M---C and C'---M' belonging in circulation. The change in value pertains exclusively to the metamorphosis P, the process of production, which thus appears as a real metamorphosis of capital, as compared with the merely metamorphosis of circulation.
Let us now consider the total movement, M---C ... P ... C'---M', or, M---C< L MP ... P ... C' (C + c)---M(M + m), its more expanded form. Capital here appears as a value which goes through a series of interconnected, interdependent transformations, a series of metamorphoses which form just as many phases, or stages, of the process as a whole. Two of these phases belong in the sphere of circulation, one of them in that of production. In each one of these phases capital-value has a different form for which there is a correspondingly different, special function. Within this movement the advanced value does not only preserve itself but grows, increases in magnitude. Finally, in the concluding stage, it returns to the same form which it had at the beginning of the process as a whole. This process as a whole constitutes therefore the process of moving in circuits.