The first volume of Das Kapital was published in 1867 at a time when the working conditions for industrial laborers were terrible and the division between the classes was growing increasingly more pronounced. It must not be forgotten that Das Kapital was a work born out of the industrial revolution.
Marx begins the first chapter of Das Kapital with a statement concerning commodities. He defines a commodity as "an object outside us, a thing that by its properties satisfies human wants of sort or another" (125). It is interesting that Marx begins the text with a discussion and definition of a commodity and after several successive chapters, it is clear to see that the commodity is one of the main driving forces behind capitalism. The commodity itself, however, is only valued according to demand or other more ethereal conditions and thus it is a perfect item for the capitalist as it presents no fixed "price" in itself, but its value is rather determined by desire and the potential for profit. To backtrack for a moment, however, a more concise definition of commodity is contained within the idea of "use value." This refers to a commodity's value in how it will be used and how it is desired but this value, according to Marx, has little to do with the actual labor that went into the production of the item. Again, while it is not immediately clear at this early point in the text, the use value versus the idea of labor are important issues because there is more distinction between the two than one might initially think. For instance, something might have a very high use-value and be greatly desired. This desire leads the capitalist to make it expensive and the laborer who made the desired commodity is not paid what the desired commodity is worth, but rather is paid living wages while the surplus profits go directly to the capitalist since he owns the means of production. While that was a very brief, concise, but altogether limited description of the process behind commodities and use value, it is useful background information to frame the discussion as this analysis continues.
After this introduction to commodities and use values in Das Kapital , the idea of exchange value becomes of equal importance. As Marx puts it in one of the important quotations from "Das Kapital", "As use values, commodities are, above all, of different qualities, but as exchange values they are merely different quantities, and consequently do not contain an atom of use value" (127). In other words, it is the proportion by which use values of one kind exchange for use values of another kind. This is a vital and fluctuating relationship and has less to do with the commodity than it might initially seem.
In short, the common element in a commodity's exchange-value is simply the "value" of it. This means that it all comes down to labor. This is a common tactic Marx employs, at first there a number of daunting methods for scientifically extracting a conception of value but in the end, it all boils down to questions about work and