Jacob Moleschott

1.1. Birth and Early Background

Jacobus Albertus Willebrordus Moleschott was born in 's-Hertogenbosch, Netherlands, on August 9, 1822. His father, Jo(h)annes Franciscus Gabriel Moleschott (1793-1857), was a physician who harbored skepticism towards religion and fostered an early interest in the natural sciences in his son. His mother was Elizabeth Antonia (or Antonetta) van der Monde (1795-1866). Moleschott attended school in Cleves, where he developed proficiency in Greek and Latin, encouraged by the school director Ferdinand Helmke. His Latin and Greek teacher, Moritz Fleischer, also introduced him to Hegelian philosophy, which would later influence his thought.

1.2. Education

Unlike his father, who studied at Leiden, Moleschott pursued medicine at Heidelberg University. During his studies, he was mentored by notable scientists: Theodor Bischoff taught him botany, and Wilhelm Delff instructed him in chemistry. He studied anatomy under Friedrich Tiedemann (1781-1861) and physiology under Leopold Gmelin (1788-1853). In 1845, he earned his PhD under the supervision of Jacob Henle. During this period, Moleschott also became involved with the intellectual circle of Johann Christian Kapp and began to forge significant scientific networks, meeting figures such as Justus Liebig in Giessen and Lorenz Oken in Bern. He actively participated in the exchange of scientific knowledge, translating the work of Johannes Mulder and sharing it with Gabriel Gustav Valentin in Bern, whose work he, in turn, passed on to Tiedemann.

1.3. Early Career and German Activities

In 1845, Moleschott moved to Utrecht to work as an assistant to Johannes Mulder, a prominent chemist. During this time, he engaged in discussions on the physiology of vision with Franciscus Cornelis Donders (1818-1889). Soon after, he returned to Heidelberg University as a Privatdozent, developing a strong interest in Mulder's work on nutrition. Moleschott's interest extended to socialism, which he believed could improve public nutrition. He became involved in a scientific debate between Liebig and Mulder regarding the role of macronutrients, which strained his relationship with Liebig. While Liebig argued that carbohydrates alone served as fuel for the body, Moleschott emphasized the crucial roles of protein and fat.

Beginning in 1847, Moleschott lectured on physiology and in 1850 published Physiologie der Nahrungsmittel, a work that garnered significant praise, including from Alexander von Humboldt. He placed particular emphasis on experimental methods in his research. He further expanded his public engagement by offering a series of lectures open to all, exploring anthropology through experimental approaches. However, his radical political positions, outspoken "brutal materialism," and atheism drew the ire of the authorities. In 1854, under orders from the Interior Ministry of Baden, Heidelberg University reprimanded Moleschott, leading to his resignation. Alongside Carl Vogt and Ludwig Büchner, Moleschott was a central figure in the public debates surrounding materialism in Germany during the 1850s.

1.4. Italian Activities and Citizenship

After his resignation, Moleschott spent two years without an academic post, during which he began working on his extensive 15-volume series, Untersuchungen zur Naturlehre des Menschen und der Thiere (Investigations into the Natural History of Man and Animals). He also penned a biography of Georg Forster, whom he admired as a "people's scientist." His nutritional theories gained practical application, influencing popular cookbooks such as Wilhelmine Rührig's Frankfurter Kochbuch (later Kochbuch fürʼs Deutsche Haus), which was based on the theories of both Liebig and Moleschott, advocating for daily protein consumption. His work also inspired essays on morality through rational thought, as seen in Mathilde Reichardt-Stromberg's use of Moleschott's Kreislauf des Lebens.

In 1856, Moleschott secured a professorship in physiology at the University of Zurich. While in Zurich, he and his wife learned Italian, a language that would become increasingly important in his later career. In 1861, he moved to the University of Turin, where he actively fostered networks among Swiss, German, and Italian researchers. His contributions to Italian science and public life were recognized in 1867 when he received Italian citizenship. He continued his efforts to popularize science, particularly physiology. In 1876, he was appointed as a Senator in the Kingdom of Italy. In 1878, he relocated to La Sapienza in Rome, taking up a professorship in experimental physiology in 1879. He utilized his political position to advocate for social justice, notably supporting the lawyer Lidia Poët when she was denied a professional position solely because she was a woman. Moleschott also publicly opposed antisemitism and the unpopular Macinato or grist tax. On June 9, 1889, he delivered a public address at the inauguration of a statue of Giordano Bruno in the Vatican, alongside a speech by Gaetano Trezza (1828-1892), emphasizing the importance of rational thought against the religious intolerance of the Church.

2.1. Scientific Materialism

Moleschott believed that the origin and condition of animals could be entirely explained by the workings of physical causes. He famously articulated his materialistic view through characteristic aphorisms, asserting that "no thought without phosphorus" and that "the brain secretes thought as the liver secretes bile." This perspective posited that life phenomena are entirely reducible to chemical processes, with human thought being merely a function of the brain's interaction with substances like phosphorus. His atheism, a direct consequence of his materialistic worldview, contributed to his dismissal from Heidelberg University.

2.2. Nutrition and Physiology

Moleschott's scientific investigations heavily focused on nutrition and metabolism. He built upon the work of Johannes Mulder regarding the physiological processes of food. He challenged the prevailing view, notably held by Justus Liebig, that carbohydrates were the sole fuel for the body. Moleschott's research highlighted the critical roles of proteins and fats in human metabolism, advocating for their daily consumption. His work, such as Physiologie der Nahrungsmittel, emphasized the importance of experimental methods in understanding physiological processes. He extended his research beyond the laboratory, delivering public lectures that explored anthropology through an experimental lens, demonstrating his commitment to making scientific knowledge accessible and relevant to broader societal issues.

2.3. Key Scientific Propositions

Moleschott's most famous propositions succinctly encapsulated his scientific materialistic philosophy:

• "No thought without phosphorus." This aphorism underscored his belief that mental processes were directly tied to the chemical composition and activity of the brain, particularly the presence of phosphorus.
• "The brain secretes thought as the liver secretes bile." This statement further emphasized his view that thought was a purely physiological product, akin to other bodily secretions, thereby rejecting any non-material or spiritual basis for consciousness.

3.1. Der Kreislauf des Lebens

Published in 1852, Der Kreislauf des Lebens (The Cycle of Life) was Moleschott's most influential work. This book articulated his physiological materialism, arguing that life processes are fundamentally chemical and physical in nature. It became a foundational text for the scientific materialist movement in Germany and profoundly influenced radical thinkers and citizens of the time. The work went through multiple editions, with the fifth edition appearing in 1887, demonstrating its enduring impact.

3.2. Other Major Writings

Moleschott's other significant publications include:

• [https://archive.org/details/lehredernahrungs00mole Lehre der Nahrungsmittel. Für das Volk] (Erlangen, 1850; 3rd edition, Erlangen, 1858)
• [https://archive.org/details/physiologiedern00molegoog Physiologie der Nahrungsmittel] (1850; second edition, 1859)
• [https://archive.org/details/physiologiedesst00moleuoft Physiologie des Stoffwechsels in Pflanzen und Thieren] (1851)
• [https://www.digitale-sammlungen.de/en/details/bsb11414995 Georg Forster, der Naturforscher des Volkes] (1854), a biography of the explorer and naturalist.
• Untersuchungen zur Naturlehre des Menschen und der tiere (Investigations into the Natural History of Man and Animals) (1856-93), a multi-volume work that was continued after his death by Colosanti and Fubini.
• Sulla vita umana (On Human Life) (1861-67), a collection of essays.
• Physiologisches Skizzenbuch (Physiological Sketchbook) (1861).
• Consigli e conforti nei tempi di colera (Advice and Comfort in Times of Cholera) (1864; third edition, 1884).
• Sull' influenza della luce mista e cromatica nell' esalazione di acido carbonico per l'organismo animale (On the Influence of Mixed and Chromatic Light on the Exhalation of Carbonic Acid by the Animal Organism) (1879), co-authored with Fubini.
• Kleine Schriften (Small Writings) (1880-87), a collection of his essays and addresses.
• Für meine Freunde (For My Friends) (1894), published posthumously.

The comprehensive archive of Jacob Moleschott's works and papers is preserved in the Archiginnasio of Bologna's public library in Italy.

4.1. Political Stance and Activities

Moleschott held radical political views for his time, which often put him at odds with conservative authorities. His advocacy for scientific engagement in politics stemmed from his conviction that scientific principles and rational thought were essential for societal betterment. His outspoken atheism and "brutal materialism" were seen as direct challenges to the established order, leading to his forced resignation from Heidelberg University in 1854. Despite this setback, he continued to champion secularism and rationalism throughout his life. His appointment as a Senator in Italy in 1876 provided him with a direct platform to influence public policy, which he used to oppose regressive measures like the grist tax.

4.2. Social Movements and Human Rights Advocacy

Moleschott's progressive ideals extended to various social movements. He was interested in socialism, particularly its potential to address issues of public health and nutrition. He actively supported women's rights, notably using his political influence to back the lawyer Lidia Poët when she was unjustly denied the right to practice law because of her gender. He was also a vocal opponent of antisemitism, a stance that reflected his broader commitment to human dignity and equality. Furthermore, Moleschott was a staunch defender of rationalism against religious intolerance. His public speech at the inauguration of the Giordano Bruno statue in Rome in 1889, a monument erected in defiance of the Catholic Church, underscored his unwavering support for intellectual freedom and critical thought against dogmatism.

7.1. Positive Assessment

Moleschott is widely recognized for his pioneering work in physiology and nutrition, particularly his emphasis on the roles of proteins and fats in metabolism, which challenged prevailing scientific views. His commitment to experimental methods and the popularization of science helped to disseminate scientific knowledge to a broader public. Beyond his scientific achievements, he is positively assessed for his contributions to social reform and humanistic causes. His advocacy for women's rights, opposition to antisemitism, and defense of rationalism against religious intolerance highlight his dedication to social justice and intellectual freedom.

7.2. Criticism and Controversy

Moleschott's outspoken materialism and atheism generated considerable controversy, particularly in conservative German academic and political circles. His philosophy was labeled "brutal materialism," leading to his forced resignation from Heidelberg University. He was a central figure in the intense public debates surrounding materialism in Germany during the 1850s, where his views were often met with strong opposition from those who saw them as a threat to traditional moral and religious values.

7.3. Influence on Posterity

Despite the controversies, Moleschott's ideas profoundly influenced subsequent scientific thought and social movements. His book, Der Kreislauf des Lebens, became a foundational text for scientific materialism and had a significant impact on radical political circles in Germany. His emphasis on the chemical basis of life and thought contributed to the development of biochemistry and neuroscience. His advocacy for the social responsibility of scientists and his engagement in human rights issues also left a lasting mark, inspiring later generations to connect scientific inquiry with broader societal concerns. His nutritional theories, advocating for balanced diets including proteins and fats, influenced popular dietary practices and cookbooks of his time.