The famous German chemist is today known as the “father of organic chemistry”; along with Friedrich Wöhler he conducted a series of experiments to analyze chemical elements to find out not only that two molecules with the same molecular formula can have different properties (an isomer) but also that millions of different kinds of organic compositions can be formed out of various combinations of the simple and presumed unchangeable structures of organic compounds, even though their assumption of unchangeability later proved false.10 After 1837, Liebig conducted research in physiological chemistry and published the epoch-making Organic Chemistry in Its Application to Agriculture and Physiology, usually simply called Agricultural Chemistry, as the aforementioned Organic Chemistry in Its Application to Physiology and Pathology is usually called Animal Chemistry. In these books Liebig applied his newest discoveries in chemistry to an analysis of the organic process of plants and animals. He investigated the reciprocal relationship of plants, animals, and humans as chemical interactions of organic and inorganic substances, even claiming that “the animal organism is a higher kind of vegetable.”11 Liebig opened up the new field of chemical analysis of metabolism, which synchronized nicely with the newly discovered law of conservation of energy.12 He was highly critical of the dominant vitalist dualism of Jean-Baptiste André Dumas and Jean Baptiste Boussignault, who postulated the clear difference between “two kingdoms of plants and animals.”13
In one of the earliest usages of the term metabolism Liebig depicted the constant interactive process of formation, transformation, and excretion of various compounds within an organic body:
It cannot be supposed that metabolism in blood, the changes in the substance of the existing organs, by which their constituents are converted into fat, muscular fiber, substance of the brain and nerves, bones, hair &c., and the transformation of food into blood, can take place without the simultaneous formation of new compounds which require removal from the body by the organs of excretion.… every motion, every manifestation of organic properties, and every organic action being attended by metabolism, and by the assumption of a new form by its constituents.14
Metabolism is an incessant process of organic exchange of old and new compounds through combinations, assimilations, and excretions so that every organic action can continue. Liebig also maintained that the chemical reaction in combination and excretion is the ultimate source of electric current as well as that of warmth and force. Liebig’s theory of metabolism prepared a scientific basis for further analyses of a living organism as pure chemical process.15
The concept of metabolism, under the influence of Liebig, soon went beyond the nourishment of individual plants, animals, and humans. That is, it could be used to analyze their interaction within a certain environment. Today’s concept of metabolism can be applied not just to organic bodies but also to various interactions in one or multiple ecosystems, even on a global scale, whether “industrial metabolism” or “social metabolism.”16 This physiological and chemical concept about an extensive organic whole in nature found a wide reception and was employed beyond natural science, in philosophy and political economy, where it has been used to describe a social metabolism by way of analogy. This was the case in Marx’s writings. However, out of this extension there emerged a certain ambiguity due to the term’s multiple meanings, and it is necessary to distinguish them with commentary.
A careful conceptual differentiation of metabolism in Marx’s writings is of importance, for there are a number of debates in the earlier literature in terms of how he integrated this concept into his political economy.17 Even if it is difficult to determine every single source of his inspiration, given that he actively modified the concept for the purpose of his own analysis, this does not mean that one can use text in an arbitrary manner as a source for the sake of justifying a certain interpretation of Marx. Liebig is without doubt one of the most important intellectual sources, as has been convincingly demonstrated by John Bellamy Foster.18 The intellectual heritage of Liebig first became manifest in Capital. Yet Marx did not simply take the concept from Liebig’s Agricultural Chemistry, in which the term metabolism appears only twice, but developed and modified the concept through his study of various texts in chemistry and physiology.
It is worth discussing Marx’s first usage of the concept of metabolism, which was not at all referred to in the earlier debates about his ecological perspective. The relevant text is in one of his London Notebooks of March 1851, titled Reflection, which was later published in the MEGA2.19 The date clearly indicates that Marx knew the concept of metabolism before his reading of Liebig’s book in July 1851.
Because of the scant attention the fourth section of the MEGA2 received, the key passages in Reflection about metabolism were not taken into account in the debates. However, the text provides a helpful hint for Marx’s reception of the physiological concept, for he was not studying natural science so intensively then, so it is safe to assume that he took up the concept right before writing Reflection.
The term “metabolic interaction” (Stoffwechsel) appears three times in Reflection:
Unlike ancient society where only the privileged could exchange this or that [item], everything can be possessed by everybody [in capitalist society]. Every metabolic interaction can be conducted by everyone, depending on the amount of money of one’s income that can be transformed into anything: prostitute, science, protection, medals, servants, cringer—everything [becomes a] product for exchange, just like coffee, sugar, and herring. In the case of rank [society], the enjoyment of an individual, his or her metabolic interaction is dependent on a certain division of labor, under which he or she is subsumed. In the case of class [it is dependent] only on the universal means of exchange that he or she can appropriate.… Where the type of income is still determined by the type of occupation, and not simply by the quantity of the universal medium of exchange like today but by the quality of one’s occupation, the relationships, under which the worker can enter into society and appropriate [objects], are severely restricted, and the social organ for the metabolic interaction with the material and mental productions of the society is limited to a certain way and to a particular content from the beginning.20
In Reflection, Marx again explicates his critique of the money system with a method of comparison between various forms of society, revealing the class antagonism hidden under the formally free and equal relationship of the bourgeois society. In order to illuminate the specificity of the mode of appropriation under the monetary system, Marx contrasts the appropriation of products in capitalist society with that in precapitalist societies, comprehending the problem as different ways of organizing the “metabolic interaction.” In this sense, the concept of “metabolic interaction” is clearly used to deal with the transhistorical character of the necessity to organize social production.
Since in the precapitalist societies the appropriation of products took place based on the direct personal and political dominance legitimated by tradition, innate privileges, and violence, the variability of labor was limited to that within a certain “rank,” and thus “the social organ for the metabolic interaction with material and mental productions of society” remained much narrower than in capitalist society. In capitalist society, the appropriation and transfer of products takes place on a much larger scale among the formally free and equal owners of commodities and money. The commodity exchange appears totally free from class conflicts, and the “metabolic interaction” seems to enlarge with an increasing amount of money. Equality and freedom “without class character,” however, soon turns out to be an “illusion.”21 In reality, the quantitative volume of money decides the “enjoyment of an individual, his metabolic interaction,” totally independent of actual concrete needs. Marx points to the brutal fact that the abstract formal equality under the system of money is inverted into the restriction of freedom and equality. To sum up, Marx in Reflection argues that the individual and social “metabolic interaction” in the capitalist mode of appropriation ends up heavily limited,
