This subsection is called “The Relative form of value” and begins with ” (a.) The nature and import of this form.”
Page 49: “In order to discover how the elementary expression of the value of a commodity lies hidden in the value-relation of the two commodities, we must, in the first place, consider the latter entirely apart from its quantitative aspect. The usual mode of procedure is generally the reverse, and in the value-relation nothing is seen but the proportion between definite quantities of two different sorts of commodities that are considered equal to each other. It is apt to be forgotten that the magnitudes of different things can be compared quantitatively, only when those magnitudes are expressed in terms of the same unit. It is only as expressions of such a unit that they are of the same denomination, and therefore commensurable.”
We’re looking, then, for the “elementary expression of the value of a commodity” as it exists in the value-relation, or, I guess, comparison, of two commodities. The first thing, then, is make the observation that, in order for two things to be comparable in quantity, we have to use the same form of measurement, or the same unit, for both of them–trying to compare the height of a tree with the weight of a truck is rarely useful. We measure the height of trees, or of any two objects whose height we wish to compare, in, for example, feet.
“Whether 20 yards of linen = 1 coat or =20 coats or =x coats–that is, whether a given quantity of linen is worth few or many coats, every statement implies that the linen and coats, as magnitudes of value, are expressions of the same unit, things of the same kind. Linen=coat is the basis of the equation.”
Page 50: “But the two commodities whose identity of quality is thus assumed, do not play the same part. It is only the value of the linen that is expressed. And how? By its reference to the coat as as its equivalent, as something that can be exchanged for it….in this relation the coat is the mode of existence of value, is value embodied, or only as such is it the same as the linen.”
The value of the linen is determined by the coat, by saying that we can exchange the coat for it and will be exchanging equal values.
“On the other hand, the linen’s own value comes to the front, receives independent expression, for it is only as being value that it is comparable with the coat…” Thus, the coat reveals the value of the linen.
“If we say that, as values, commodities are mere congelations of human labour, we reduce them by our analysis, it is true, to the abstraction, value; but we ascribe to this value no form apart from their bodily form. It is otherwise in the value-relation of one commodity to another. Here, the one stands forth in its character of value by reason of it’s relation to the other.”
When we discuss value by comparing one commodity to another, we find that value because it is makes then equal. When looking at value by itself, within a single, given commodity, we do so by abstracting out all characteristics of that commodity except that it is the embodiment of human labor.
“Now, it is true that the tailoring, which makes the coat, is concrete labour of a different sort from the weaving which makes the linen. But the act of equating it to the weaving, reduces the tailoring to that which is really equal in the two kinds of labour, to their common character of human labour. In this roundabout way, then, the fact is expressed, that weaving, also, in so far as it weaves value, has nothing to distinguish it from tailoring, and, consequently, is abstract human labour. It is the expression of equivalence between different sorts of commodities that alone brings into relief the specific character of value-creating labour, and that it does by actually reducing the different varieties of labour embodied in the different kinds of commodities to their common quality of human labour in the abstract.”
Here we have a footnote, in which Marx cites Ben Franklin, quoting him as saying, “Trade in general being nothing else but the exchange of labour for labour, the value of all things is…most justly measured by labour.” The point, here, is that, just as we are able to reduce the linen and the coat to values because they embody human in labor, so, too, the labor of producing them is, economically, reduced to abstract human labor.
Page 51: “Human labour-power in motion, or human labour, creates value, but is not itself value. It becomes value only in its congealed state, when embodied in the form of some object. In order to express the value of the linen as a congelation of human labour, that value must be expressed as having objective existence, as being something materially different from the linen itself, and yet a something common to the linen and all other commodities. The problem is already solved.”
“In the production of the coat, human labour-power, in the shape of tailoring, must have been actually expended. Human labour is therefore accumulated in it. In this aspect, the coat is a depository of value. In this aspect the coat is a depository of value, but though worn to a thread, it does not let this fact show through. And as equivalent of the linen in the value equation, it exists under this aspect alone, counts therefore as embodied value, as a body that is value. A, for instance, cannot be “your majesty” to B,unless at the same time majesty in B’s eyes assumes the bodily form of A, and, what is more, with every new father of the people, changes its features, hair, and many other things besides.
“Hence, in the value equation, in which the coat is the equivalent of the linen, the coat officiates as the form of value. The value of the commodity linen is expressed by the bodily form of the commodity coat, and the value of one by the use-value of the other. As a use-value, the linen is something palpably different from the coat; as value, it is the same as the coat, and now has the appearance of a coat. The fact that it is value, is made manifest by its equality with the coat, just as the sheep’s nature of a Christian is shown in his resemblance to the Lamb of God.”
Irony? Oh, we don’t get that here.
The value of commodities is revealed by their relationship to other commodities. The bodily form of A is the value-form of B. This is the form of relative value–ie, relative to another commodity, expressed in terms of another commodity.