[I]t is the concrete structure of commodity production which forms the starting point of all Marx’s reflections and in no way the purely logical comparison of two commodities.

Marx thus starts out from the fact of the universal equalisation of all commodities with each other, or from the fact that every commodity can be compared with a vast number of other commodities. Nevertheless this assumption alone is not adequate for all the conclusions Marx draws. There is another tacit assumption underlying these which Marx expressed elsewhere.

The second assumption consists in this: we assume that the exchange of a quarter of wheat for any other commodity, is an exchange which is governed by a known regularity (Gesetzmässigkeit), and the regularity of these acts of exchange is due to their dependence on the process of production. We have to reject the notion that the quarter of wheat can be exchanged for any random quantity of iron, coffee etc. We cannot agree with the assumption that the proportions of exchange are laid down each time in the act of exchange itself, and so have a completely accidental character. We maintain that all these possibilities for the exchange of a specific commodity with another, are governed by a determined regularity which is based in the process of production. In this case Marx’s whole argumentation takes the following form:

Marx says: let us take not the accidental exchange of two commodities wheat, and iron, but exchange in the form in which it actually occurs in commodity production, and then we will see that each object can be universally equated with all other objects; in other words, we can observe countless numbers of proportions of exchange of a given product with all others. But the proportions of the exchange are not accidental, they are regular, and their regularity is determined by causes which are grounded in the process of production.

Thus we reach the conclusion, that independently of the fact that the value of a quarter of wheat is expressed on one occasion as two pounds of coffee, on another as three chairs etc., the value of a quarter of wheat remains one and the same in all the different cases. If we were to assume that a quarter of wheat has a different value in each of the infinite number of proportions of exchange — and Bailey’s assertions amount to this — then we would be acknowledging that complete chaos reigns in the phenomenon of price formation, in that sublime phenomenon of exchange of products, through and by means of which a universal inter-relation of all modes of labour is established.