Mr. Mill has here used cost of production almost exactly in the sense of cost of labor, and as excluding profit (while in the next chapter he includes some part of profit in the analysis). It will be well, for the sake of definiteness, to collect the phrases above in which he describes cost of production: “Unless that value is sufficient to repay the cost of production, and to afford, _besides_, the ordinary expectation of profit, the commodity will not continue to be produced”; “the cost of production, _together with_ the ordinary profit, may therefore be called the _necessary_ price, or value”; “it repays the cost of production, not only _with_ the customary, but _with_ a higher rate of profit”; “the cost of production with the ordinary profit—in other words, such as will give to all producers the same rate of profit on their outlay”; “that the profit may be equal where _the outlay, that is, the cost of production_, is equal.” This is a view which distinctly uses cost of production in the sense of the outlay to the capitalist, or cost of labor. In no other way can profit vary with “cost of production” than in the sense that it is what a given article “costs to the capitalist”; but that is Mr. Mill’s definition of cost of labor (p. 227). It is, however, very puzzling when in the next section he speaks of “the natural value, that is, the cost of production.” Above, value included cost of production and profit also. Having thus pointed out what is Mr. Mill’s conception of cost of production, it will remain for us in the next chapter to consider whether any other view of it is more satisfactory. Adam Smith and Ricardo have called that value of a thing which is proportional to its cost of production, its Natural Value (or its Natural Price). They meant by this, the point about which the value oscillates, and to which it always tends to return; the center value, toward which, as Adam Smith expresses it, the market value of a thing is constantly gravitating; and any deviation from which is but a temporary irregularity which, the moment it exists, sets forces in motion tending to correct it. On an average of years sufficient to enable the oscillations on one side of the central line to be compensated by those on the other, the market value agrees with the natural value; but it very seldom coincides exactly with it at any particular time. The sea everywhere tends to a level, but it never is at an exact level; its surface is always ruffled by waves, and often agitated by storms. It is enough that no point, at least in the open sea, is permanently higher than another. Each place is alternately elevated and depressed; but the ocean preserves its level. § 6. The Value of these Commodities confirm, in the long run, to their Cost of Production through the operation of Demand and Supply.