In accordance with the quid pro quo, by which the revenue becomes the source of commodity-value instead of the commodity-value being the source of revenue, the value of commodities new has the appearance of being “composed” of the various kinds of revenue; these revenues are determined independently of one another, and the total value of commodities is determined by the addition of the values of these revenues. But now the question is how to determine the value of each of these revenues which are supposed to form commodity-value. In the case of wages it can be done, for wages represent the value of their commodity, labour-power, and this value is determinable (the same as that of all other commodities) by the labour required for the reproduction of this commodity. But surplus-value, or, as Adam Smith has it, its two forms, profit and rent, how are they determined? Here Adam Smith has but empty phrases to offer. At one time he represents wages and surplus-value (or wages and profit) as component parts of the value, or price, of commodities; at another, and almost in the same breath, as parts into which the price of commodities “resolves itself”; but this means on the contrary that the commodity-value is the thing given first and that different parts of this given value fall in the form of different revenues to the share of different persons engaged in the productive process. This is by no means identical with the notion that value is “composed” of these three “component parts.” If I determine the lengths of three different straight lines independently, and then form out of these three lines as “component parts” a fourth straight line equal to their sum, it is by no means the same procedure as when I have some given straight line before me and for some purpose divide it, “resolve” it, so to say, into three different parts. In the first case, the length of the line changes throughout with the lengths of the three lines whose sum it is; in the second case, the lengths of the three parts of the line are from the outset limited by the fact that they are parts of a line of given length.