early the source from which the ten and twenty years' interest flows, and the only source from which it can flow.
Thus this exception to the law of labour-value is nothing less than the chief feature in natural interest on capital. Any one who would explain natural interest must, in the first place, explain this; without an explanation of the exception here can be no explanation of the problem of interest. Now if, notwithstanding, in treatises on interest this exception is ignored, not to say denied, it is as gross a blunder as could well be conceived. When Rodbertus ignores the exception, it means nothing else than ignoring the chief part of what he ought to have explained.
Nor can one excuse Rodbertus's blunder by saying that he did not intend to lay down a rule which should hold in actual life, but only a hypothetical assumption by which he might carry through his abstract inquiries more easily and more correctly. It is true that Rodbertus, in some passages of his writings, does clothe the proposition, that the value of all goods is determined by their labour costs, in the form of a simple hypothesis.*46 But, firstly, there are many passages where Rodbertus expresses his conviction that his principle of value also holds in actual economic life.*47 And, secondly, a man may not assume anything that he likes, even as a simple hypothesis. That is to say, even in a purely hypothetical assumption, one may omit only such circumstances of actual fact as are irrelevant to the question under examination. But what is to be said for a theoretical inquiry into interest which at the critical point leaves out the existence of the most important feature; which gets rid of the principal part of what it had to explain with a "let us assume"?
On one point it may be admitted that Rodbertus is right: if we wish to discover a principle like that of land-rent or interest, we must "not let value dance up and down";*48 we must assume the validity of a fixed law of value. But is it not also a fixed law of value that goods which require a longer time between the expenditure of labour and their completion have, ceteris paribus, a higher value? And is not this law of value of fundamental importance in relation to the phenomenon of interest? And yet it is to be left out of account like an irregular accident of the circumstances of the market!*49
This singular omission is not without result. On the first result I have already touched. In overlooking the influence of time upon the value of products, Rodbertus could not avoid falling into the mistake of confounding the claim of the labourer to the whole present value of his product with the claim to its future value. Some other consequences we shall encounter shortly.
A fourth criticism which I have to make on Rodbertus is, that his doctrine contradicts itself in important points.
His entire theory of land-rent is based upon the repeatedly and emphatically expressed proposition that the absolute amount of "rent" to be gained in a production does not depend upon the amount of the capital employed, but exclusively upon the amount of labour connected with the production.
Supposing that in a certain industrial production—for example, in a shoemaking business—ten labourers are employed. Each labourer produces per year a product of the value of £100. The necessary maintenance which he receives as wages claims £50 of this sum. Thus, whether the capital employed be large or small, the year's rent (as we shall call it with Rodbertus) drawn by the undertaker will amount to £500. If the capital employed amounts, say to £1000, namely, £500 for wages of labour and £500 for material, then the rent will make up 50 per cent of the capital. If in another production, say a jeweller's business, ten labourers likewise are employed, then, under the assumption that the value of products is regulated by the amount of labour incorporated in them, they also will produce another yearly product of £100 each, of which the half falls to them as wages, while the other half falls to the undertaker as rent. But as in this case the 