that result from labor may be thought to be economic goods; other goods, like sunlight, which do not result from labor are natural goods and consequently have nothing to do with economics. Second, an economic good is solely the product of the labor; any other view of it is to be left to physicists. No part of the value of grain, for example, is to be attributed to sunshine or soil. Third, economic goods are products of the labor that went into their composition and the labor that created the instruments that enabled that production. The value of grain, for example, is not to be found merely in the ploughman but also in the work of those who manufactured the plough. Eugen von Böhm-Bawerk thought that Rodbertus' exposition of the exploitation theory was superior to that of Karl Marx in profundity and coherence. However, Böhm-Bawerk published his Capital and Interest, where he made his poignant criticism of the theory of exploitation and the labor theory of value on which it is founded, in 1890, several years before the publication of Volume III of Capital (most of which was written in the 1860s). There, Marx eliminates his simplifying assumption of Volume I that in capitalism commodities tend to exchange according to their 'values' (i.e., labor-values). Without Volume III it is not possible to have the complete picture of Marx's theory of capitalism and, in particular, his theory that commodities exchanged according to their 'production prices', which deviated systematically from their 'values', or according to 'modified prices of production' if capitalists had to pay rent to landowners. For Marx, commodities tended to exchange according to their 'values' only in non-capitalist (or 'simple') commodity production in which there is no wage labor (only independent producers) and land is freely available. Nevertheless, he used his sophisticated labor theory of 'value' for the construction of his theory of surplus-value (which was his theory of exploitation). This was the 'esoteric' part of his theory, which underlaid the 'exoteric' part that explained equilibrium prices, wages, and rents. The global surplus-value produced was for him the foundation for profits on capital and rents on land. Böhm-Bawerk considered the labor theory of value fallacious, since it could only be valid in special cases. For example, he argued against Rodbertus that a nugget of gold that falls to earth embedded in a meteorite, and thus not having been produced by