Marx used the concept of metabolism in Reflection, and not in the earlier part of the London Notebooks. Despite this fact, it is possible to find out the source. Gerd Pawelzig, in his analysis of Marx’s concept of metabolism, offers the information that in February 1851 Marx received from his friend Roland Daniels a manuscript for a book titled Mikrokosmos: Entwurf einer physiologischen Anthropologie.22 Daniels was an “excellent, scientifically educated doctor” according to Marx and Engels, and he was a member of the Communist League.23 His intellectual relationship with Marx was built on a close friendship, and Marx dedicated his book The Poverty of Philosophy to Daniels.
Daniels wrote to Marx in a letter of February 8, 1851, asking for a “sharp and candid” critique of his manuscript.24 As he explained in his next letter, the principal aim of his Mikrokosmos was to ground, in contrast to the spiritualist theory, “the possibility” to understand “human society in a materialist manner,” based on a “physiological description of activity.”25 Daniels conveyed to Marx that he was attempting to apply the newest physiological knowledge in order to treat the material and mental activity of humans on both individual and social levels as an object of (materialist) scientific investigation. In this context metabolism played an important role. Notably, Daniels used the term in his very first letter to Marx: “I would risk my organic metabolism against a mental metabolism, and I doubt if I would be able to digest and assimilate so many things well to reproduce something ordinary.”26
Marx carefully studied Daniels’s manuscript in the next month and commented on it critically, as Daniels had asked in his letter dated March 20.27 The first usage of the concept of “metabolism” in Reflection is certainly closely connected with his critique of Daniels’s Mikrokosmos, as both texts were written in the same month. Pawelzig was nonetheless not conscious of the relevant paragraph in Reflection and simply concluded that Marx and Engels in 1851 did not use the term metabolism in their notes and letters.28 But this statement is incorrect.
In Daniels’s Mikrokosmos, the concept of “organic metabolism” appears many times. For instance, he defines it as “simultaneous destruction and regeneration, through which these bodies maintain their individuality as they incessantly and newly produce this individuality—this is a uniqueness whose analogy cannot be found in inorganic bodies.”29 Though there is some affinity between Daniels and Liebig in their treatment of metabolism, Daniels’s discussion displays his originality when he divides “organic metabolism” into “animal and mental metabolism” and criticizes the ungrounded supposition of “vital force.”30 His materialist understanding of mental metabolism is directed both against the philosophical dualism of “body” and “spirit” and against the Hegelian speculative philosophy of “absolute spirit.”31 Nonetheless, Daniels’s materialist orientation tends toward a naïve materialism because he interprets human thought, freedom, and history as pure “nerve physiological” phenomena.32 Even if Daniels, in accordance with Marx’s German Ideology, sometimes demands historical explanation through an analysis of “each type of production of material needs of life,” he tends to reduce all dimensions of human activities to a compound of pure physiological—and thus totally ahistorical—“reflex movement” that functions independently of historical production. Consequently, his theory turns out to be mechanistic and deterministic. Marx was not really content with Daniels’s Mikrokosmos, as he reported to Engels: “What little sense there is in his letter is a reflection of my own to him.”33
Marx’s critique of Daniels does not mean that he entirely dismissed the importance of the manuscript. Daniels’s replies to Marx’s criticisms indicate that he patiently provided him with critical comments and explanations to his questions. Even if Marx did not accept the general direction of Daniels’s materialist project, intensive discussions between them prompted Marx to use the concept of metabolism in his private notes in Reflection, and he came to be more interested in physiology, as documented in the London Notebooks after July 1851, most notably in excerpts from Liebig’s work. Marx shared an opinion with Daniels that the new physiological concept could be usefully applied to social analysis. In this vein, Marx used the concept not only in terms of “enjoyment of the individual,” in the sense of consumption and digestion, but also in the context of “material and mental production” on a social scale. Using the analogy to physiological metabolism, he endeavored to comprehend the modern social dynamics of production and consumption where, under a particular form of social division of labor, individuals as organs for “material” and “mental” production are ruinously alienated and impoverished. In Reflection, Marx applied the new concept to national economy, following in this sense the direction of Daniels’s program: “The theory of human organism and its relationship to society and nature also builds the sole stable foundation for the reform of the communal institution, that is, for the reform of society.”34
Unfortunately, further intellectual exchange between Marx and Daniels was interrupted when the latter was arrested in June 1851 in Cologne because of his political activity. He suffered terrible conditions in prison, and after his release died, on August 29, 1855. Marx wrote on September 6, 1855, to his widow, Amalie Daniels:
It is impossible to describe the grief I felt on hearing that dear, unforgettable Roland had passed away.… Seen amongst the others in Cologne, Daniels always seemed to me like the statue of a Greek god deposited by some freak of fate in the midst of a crowd of Hottentots. His premature decease is an irreparable loss not only to his family and friends but also to science, in which he gave promise of the finest achievements, and to the great, suffering mass of humanity, who possessed in him a loyal champion.… It is to be hoped that circumstances will some day permit us to wreak upon those guilty of cutting short his career vengeance of a kind sterner than that of an obituary.35
Even if Marx did not discuss the concept in detail in Reflection, his reading of Mikrokosmos clearly prepared a foundation for the further integration of natural sciences into political economy before his excerpts from Liebig’s Agricultural Chemistry.
Subsequently, Marx’s usage of the term metabolism became more general and systematic during the process of witing the Grundrisse. In the passage from the Grundrisse quoted above, Marx deals with the incessant interaction between humans and nature with this physiological analogy, treating nature as the inorganic body of humanity. In this vein, Marx discusses the labor process as “metabolic interaction with nature,” that is, as material interaction of three moments of production taking place within nature: raw materials, means of production, and human labor. According to Marx, this “production process in general” is “common to all social conditions” as long as humans produce within nature.36 Humans must work and produce, constantly taking out raw materials from nature, modifying nature to create various means of production and subsistence, and giving back waste materials. Labor is an essential moment in this process, and it is a transhistorical and material activity in nature, which Marx also calls “natural force.”37 After comprehending these three moments, Marx then analyzes how this incessant material exchange between humans and nature transforms itself when it receives a specific capitalist function as “valorization process of capital.” This point is the most important aspect, and I will come back to this theme in the next chapter.
In the Grundrisse, there are other meanings of metabolism that Marx continued to use until Capital. “Changes of material (Stoffwechsel = metabolism)” is contrasted with “changes of form (Formwechsel).” “Change of form” signifies exchanges of economic forms between money and commodity during the circulation process—“C-M-C” and “M-C-M”—and “change of material” has to do with the constant changes among use values within capitalist society:
Simple circulation consisted of a great number of simultaneous or successive exchanges.… A system of exchanges,
