That the theory, even when it recognises the influences of national economy upon value, in some sort paves the way for politics, is not likely to be denied. The man who has thought out the theory of value to the end, even within the limits just mentioned, will have cause to point with pride to the help which this has afforded him in political science and practical statecraft. It is a matter of the first importance -- one without which no decision can be arrived at, -- to recognise that there is a sphere within which the estimate of exchange value is applicable, and another in which it is not. Now if we could define these spheres, even in the most general way; if we could keep entirely and clearly separate the laws of the national estimate and the laws of the private estimate of value, so that every one who followed with sufficient earnestness would be convinced that they corresponded to the essential demands of economic action; if it were possible, besides, to indicate the directions in which the actual course of things diverges from these laws most frequently and with the most serious results: in that case the foundation for political action would be so plainly laid down, and would compare so well with all the errors and difficulties which beset its path without these principles, that no one would deny that such a theory had justified its existence.
To mention only one special case. The representing of goods by weighed and counted sums of barren metal or paper, and the consequent valuation of goods, and of the well-being they secure, by numbers and figures, by items and weights, is in itself a somewhat mysterious matter; a matter which a man who wishes to obtain a clear view of things might imagine to have an artificial and unhealthy origin; a matter which does, in fact, lead many an honest and intelligent thinker to such a conjecture. It is, then, a conclusion well worthy of consideration when a science succeeds in proving that such a manner of procedure is, at bottom and in its own place, sound and simple, and that it would be impossible to obtain a more exact and distinct measure for the thousandfold variety of economic satisfactions, than that afforded, under the necessary conditions, by the natural marginal value of goods.
NOTES:
1. We may take as illustration the case of a barren island whose occupation is demanded by military or political considerations.
2. Even in private economy, all thing considered, one has to deal with masses of goods and with wants of great compass: private undertaking are in fact more numerous than state undertaking, and form the principal part of the body economic. All the same, the extent of the undertaking, in private economy, has only to a trifling extent that indefiniteness of valuation which it so easily gives rise to in national economy. In private economy one has to deal with more, but smaller objects; in state economy, with isolated but more wide-reaching matters. In the former all quantities finally resolve themselves into divisible sums; in the latter, they do not. This contrast is so important, and recognition of it affords so deep an insight into the structure of exchange value, that, at the risk of repeating myself, I shall try once more to give to it as exact expression as possible.
There are two considerations which must be carefully taken into account if we would understand the calculus of private economy.
First: all stocks of goods of a similar kind -- and, along with these, all goods which, as products, relate themselves through costs to such stocks -- come within the range of the marginal law, and are measured as divisible sums made up of the smallest units, each unit estimated at one and the same value.
