Claude-Nicolas Le Cat
Traité de la couleur de la peau humaine en général, Le Cat, Claude-Nicolas, 1765, The Wellcome Collection
Claude-Nicolas Le Cat’s Treatise on the color of human skin in general, that of the nègres in particular, and the metamorphosis of one color into the other, either from birth, or by chance reveals how elite medical practitioners thought about blackness and experimented on Black bodies during the 1760s, a key period for the development of anatomical ideas of race and, eventually, modern scientific racism.[1] Le Cat’s work on skin was rooted in a highly dynamic understanding of the human body. Yet despite his focus on “metamorphoses” from one skin color to another, a deeper and more fixed understanding of race is implicit in/throughout the text is: the categories of “white” and “Nègre” (also “Ethiopian” or, less frequently, “Moor”) remained static. The book ultimately speaks to the hardening and biologizing of race as a scientific category. How, then, did Le Cat reconcile his essentializing ideas of race with the many metamorphoses recounted in his book?
Le Cat was a proponent of “vitalism,” a prominent medical theory in eighteenth-century France. While most European practitioners understood the body as reactive, shaped by environmental, physical, or emotional forces, French vitalists went particularly far in this conviction. They thought holistically about the body, arguing that it was governed by an overarching sensibility. Subtle and volatile vital fluids helped the body function, but they could also respond dramatically, even dangerously, to external stimuli.[2] In such a system, intense shock or grief could cause someone’s health to fail abruptly. Even an experience as seemingly pleasant as smelling roses could lead to sudden death, if exposure was too intense and too long.[3] The nervous system occupied pride of place in this theory, with external stimuli setting off internal chain reactions via the nerves. Le Cat drew heavily on ideas about vitalism and sensibility in articulating his own views on physiology (in fact, he theorized that bodies were so reactive that they could even spontaneously combust).[4]
These beliefs shaped Le Cat’s explanation of skin color and led him to focus on the nerves (a central mechanism in vitalist thought).[5] He theorized that the optic nerve produced an inky fluid called the “œthiops animal.” Present in all human bodies in varying quantities, the œthiops was not particular to Africans. The nerves helped spread this fluid throughout the body; the houpes nerveuses (dermal papillae) was the mechanism by which the œthiops permeated and colored the skin. A variety of factors (some hereditary and permanent, others temporary) influenced the quantity of œthiops in the body and how readily the nerves spread it around. This was an innovative explanation for differences in skin color, one that set Le Cat’s theory in square opposition to the major theories of race circulating at the time. Some scholars, such as Pierre Barrère, argued that blackness was caused by an excess of black bile circulating through the blood. Le Cat devoted whole chapters of his book to refuting this thesis. He likewise rejected climate-based explanations, such as those favored by Georges-Louis Leclerc de Buffon. Le Cat, by contrast, advanced a theory of blackness that — like vitalism more broadly — was holistic, present throughout the body (including the brain), and dynamic.
Le Cat’s treatise is fundamentally about metamorphoses: how and why Black people’s skin could turn white, and vice versa. Le Cat’s vitalism explains both his interest in this question and how he answered it. Illnesses, pregnancies, emotional shocks, maternal imagination: all of these could significantly alter the production of œthiops and functioning of the houpes nerveuses, thereby prompting dramatic changes in skin color. While some changes were permanent, others could reverse as quickly as they appeared. Although he noted that certain metamorphoses could be distressing, as in the case of a Rouennais woman whose skin blackened and apparently made her look very “frightening,” for the most part, Le Cat presented metamorphoses as intriguing and instructive rather than alarming.
Perhaps Le Cat was not alarmed because so many of these metamorphoses were temporary, particularly those that entailed white people turning black. But it seems to me that something deeper was in play: because Le Cat’s understanding of race involved the whole body, changes to skin color— especially temporary changes —did not actually trouble racial categories. Even when discussing dramatic changes in pigmentation, Le Cat never stopped referring to subjects as “white”/“European” or “Negro”/“Ethiopian”; their racial identity did not shift along with their skin color. In this work, as elsewhere, race became a more fixed and biological category in the 1760s and 1770s. Moreover, there is still much important work to be done on the connections between vitalism and racism.
How Le Cat advanced these ideas is likewise significant and reveals the institutions that supported European race-making. Drawing extensively on reports presented at and published by academies and learned societies (particularly the Royal Society of London), Le Cat’s research shows how the Republic of Letters in seventeenth- and eighteenth-century Europe influenced the development of medical and scientific racism. Hospitals and medical networks were even more crucial. Le Cat conducted many experiments and observations himself, taking full advantage of his position as chief surgeon at the Rouen Hôtel-Dieu. Although he only treated a few Black patients himself, he autopsied each one, strictly to satisfy his own curiosity. His position also connected him to a larger community of surgeons throughout France. Asking colleagues to send him samples of bodily fluids (blood, lymph) from Black patients in their hospitals, Le Cat then experimented with these materials in his own hospital, even sharing them with guests at social events. While Le Cat spent his entire career in Rouen, the evidence and ideas in this text tied him to a network of surgeons in metropolitan France and across the continent working together as agents of empire to develop new ideas and categories of race.
Meghan K. Roberts
Bowdoin College
[1] Andrew S. Curran, The Anatomy of Blackness: Science and Slavery in an Age of Enlightenment (Johns Hopkins University Press, 2011); Hannah Murphy, “Re-Writing Race in Early Modern European Medicine,” History Compass 19, no. 11 (2021).
[2] Anne C. Vila, Enlightenment and Pathology: Sensibility in the Literature and Medicine of Eighteenth-Century France (Baltimore: Johns Hopkins University Press, 1998), 13-79.
[3] Carolyn Purnell, The Sensational Past: How the Enlightenment Changed the Way We Use Our Senses, (New York: W.W. Norton), 37.
[4] Meghan K. Roberts, “Spontaneous Human Combustion and Claude-Nicolas Le Cat’s Hunt for Fame,” The Journal of Modern History 93, no. 4 (December 2021): 749–82.
[5] See also Marco Menin, “L’organe du toucher et la neurologie du racisme : l’origine tactile de la couleur de la peau chez Claude-Nicolas Le Cat,” Archives Internationales d’Histoire des Sciences (December 2021); Guillaume Linte, “La couleur de la peau dans le discours médical (1730-1770),” Dix-huitième siècle 51, no. 1 (2019): 261–74.