hich is embodied the labour of one year, must now possess a full fifth part of the value which the completed product, in which is embodied five years of labour, will possess. In this case the claim of the labourer to receive as wages a full fifth part of that completed value would be justified. But this assumption, as Rodbertus puts it, is undoubtedly false. To prove this I need not question in the least the theoretical validity of Ricardo's celebrated theory, that labour is the source and measure of all value. I need only point out the existence of a distinct exception to this law, noticed by Ricardo himself and discussed by him in detail in a separate chapter, but, strangely enough, passed over without notice by Rodbertus. This exception is found in the fact that, of two goods which have cost an equal amount of labour to produce, that one obtains a higher exchange value the completion of which demands the greater advances of previous labour, or the longer period of time. Ricardo notices this fact in a characteristic manner. He declares (§ 4 of the first chapter of his Principles) that "the principle that the quantity of labour employed in the production of goods regulates their relative value, suffers a considerable modification by the employment of machinery and other fixed and durable capital," and further, in § 5, "on account of the unequal durability of capital, and of the unequal rapidity with which it is returned to its owner." That is to say, in a production where much fixed capital is used, or fixed capital of a greater durability, or where the time of turn-over on which the floating capital is paid back to the undertaker is longer, the goods made have a higher exchange value than goods which have cost an equal amount of labour, but into the production of which the elements just named do not enter, or enter in a lesser degree,—indeed an exchange value which is higher by the amount of the profit which the undertaker expects to obtain.
That this exception to the law of labour-value noticed by Ricardo really exists cannot be questioned, even by the most zealous advocates of that law. Just as little can it be questioned that, under certain circumstances, the consideration of the postponement may have even a greater influence on the value of goods than the consideration of the amount of labour-costs. I may remind the reader, for example, of the value of an old wine that has been stored up for scores of years, or of a hundred years old tree in the forest.
But on that exception hangs a tale. It does not require any great penetration to see that the principal feature of natural interest on capital is really involved in it. For when, on the division of the value, those goods that require for their production an advance of foregoing labour show a surplus of exchange value, it is just this surplus that remains in the hands of the capitalist-undertaker as profit. If this difference of value did not exist natural interest on capital would not exist either. This difference of value makes it possible, contains it, is identical with it.
Nothing is more easily demonstrated than this, if any proof is wanted of so obvious a fact. Supposing each of three goods requires for its making a year's labour, but a different length of time over which the labour is advanced. The first good requires only one year's advance of the year's labour; the second a ten years' advance; the third a twenty years' advance. Under these circumstances the exchange value of the first good will, and must be, sufficient to cover the wages of a year's labour, and, beyond that, one year's interest on the advanced labour. It is perfectly clear that the same exchange value cannot be sufficient to cover the wages of a year's labour, and a ten or twenty years' interest on the ten or twenty years' advance of labour as well. That interest can only be covered if and because the exchange value of the second and third good is correspondingly higher than that of the first good, although all three have cost an equal amount of labour. The difference of exchange value is cl