We have seen that conceiving the commodity as exchange value means positing the expression of its exchangeability in relation to all commodities. This exchange relation, between one commodity and all, requires mediation, and this mediation is achieved through “the symbol of the commodity as commodity”. This “symbol” is money, and is itself the result of the social process of exchange. In turn, the commodity that serves as money, itself a symbol of the commodity’s general exchangeability, can itself be replaced by a symbol—a symbol of a symbol, as it were: “the commodity which is required as medium of exchange […][,] [which] becomes transformed into money, […] can in turn be replaced by a symbol of itself. It then becomes the conscious sign of exchange value.”

More (pdf, 269 KB): The Chapter on Money Part 3: Money and Exchange Value (pp. 144-156)