4. We come shortly to the explanation that nearly corresponds with Adam Smith’s “empirical account.” Here the scene is the social economy. Cost of production—always the sum of labor and abstinence—must be divided into (a) cost on the part of the producer or seller and (b) on the part of the consumer or purchaser. The latter is the amount of labor and abstinence which would have to be undergone by the consumers if they themselves, or some of them in behalf of themselves and the others, were to resort to producing the good in question instead of buying it. The former cost sets the minimum limit to price, or exchange value. The latter sets the maximum. Under circumstances of free competition, when no producer possesses any advantage over another, these two limits coincide, and the price of commodities therefore represents the aggregate amount of labor and abstinence necessary to continue their production.[145] This division of cost into two parts, each forming a limit, is Senior’s peculiar and inferior way of describing the action of competition among producers. He concludes nearly in the ordinary way: “If the price should rise beyond the cost of their [the commodities’] production, the producers must receive more than an average remuneration for their sacrifices. As soon as this has been discovered capital and industry flow towards the employment which, by this supposition, offers extraordinary advantages. Those who formerly were purchasers, or persons on their behalf, turn producers themselves, until the increased supply has equalized the price with the cost of production.”[146] The reverse movement, of course, prevents an abnormal fall of prices. This process of bringing exchange values into proportion to subjective costs of production, reduces itself simply to the adjustment of values to such a level that the wages and profits into which they are divided in each industry furnish the regular or average (as we should say, “static”) remuneration to the labor and abstinence required for production. 5. We see, then, that where labor and abstinence are the only “obstacles” to supply, or where profits and wages are the only shares which “enter into” price, values will be in proportion to cost of production, which is not labor, but a “sum of labor and abstinence.” The next question is, in what light does Senior regard _rent_. Rent, in his view, overturns the whole correlation of value with subjective cost of production. And here we are introduced to Senior’s remarkable extension of the concepts of _rent_ and of _natural agents_. In the first place, rent is defined to be the return to natural agents which are not universally accessible (p. 90). But in the second place, rent is defined to be the surplus of value produced above the amount required to remunerate the sacrifices of production.