Brown Bag Lecture: Père Castel and the Cogs of Chymistry

The Jesuit geometer and natural philosopher Louis-Bertrand Castel (1688–1757) had something to say on just about every topic. Best remembered today for his “color harpsichord” (a musical instrument that purported to harmonize colors with sounds), for his popularization of mathematics, and for his quarrels with Newtonians, he was also a prolific “journalist,” authoring hundreds of essays and book reviews, which together form a vast historical commentary on contemporary arts and sciences. Alchemy, chymistry, and matter theory are no exception to this.

There are many different entry points into Père Castel’s contribution to early-18th-century chymistry, ranging from his theory of artificial, man-made mixtures and their impact on the weather, to his system of the weight of fire, passing by periodical criticisms of contemporary alchemists in the Mémoires de Trévoux. Here I would like to focus on the matter theory he developed in his works on gravity, which I argue provides an eloquent example of an 18th-century attempt to reduce the complexity of chemical phenomena to a physical substratum—a late instance of what might be called Cartesian or Mechanical chemistry. In his analysis all phenomena (and gravity in particular) could be reduced to the repulsive effort of elementary particles conceived of as spherical cogs, whose formal properties determined their homogeneity, heterogeneity, and fermentation potential. Activated by subtle matter and disrupted by the action of “free spirits” (God and human beings), these “little machines” were to reconcile Aristotelian notions of form with the mechanical requirement of physics and the empirical complexity of chymistry.

Jean-Olivier Richard was born in 1986 in a suburb of Montreal, Canada. He received his bachelor’s degree of arts from Concordia University (Montreal) in 2009 and completed his PhD in the history of science and technology department at Johns Hopkins University in 2016. His dissertation, “The Art of Making Rain and Fair Weather,” explores the life and world system of the French Jesuit polymath Louis-Bertrand Castel (1688–1757), with a particular emphasis on his theory of the action of man on nature. J-O’s main areas of interest include early modern and Enlightenment natural philosophy and chemistry, encyclopedic endeavors, and the relationship between science and religion. Other interests include New France’s intellectual and military history, as well as cognitive sciences. He has published an article in the Revue d’histoire de l’Amérique Française entitled “Bougainville à la lumière de ses lectures: Les références classiques dans les Écrits sur le Canada.” In his spare time Jean-Olivier teaches tai-chi and volunteers for Action Haiti, a Quebec-based organization working with Haitian schools.