Chemistry and Medical Debate: van Helmont to Boerhaave (review)

For more than forty years, Allen Debus has been challenging the canonic narrative of the Scientific Revolution. This latter focused on revolutionary developments in astronomy and mechanics, the ascendancy of the mechanical philosophy, and the forging of an intersubjective experimental and quantitative method. It has an elegant narrative structure: clearly marked termini of great significance (Copernicus, 1543; Newton, 1687), and a dramatic and progressivist unfolding that subsumes the achievements of Tycho, Kepler, Galileo, Descartes, and Huyghens; all are brought into satisfying synthesis by Newton in his Principia Mathematica. Little wonder at its canonic success!

The only problem with it is that it leaves out much of what fascinated (or irritated) those interested in what constituted “natural philosophy” in the sixteenth and seventeenth centuries. In particular, it ignores the medical and the chemical sciences. Debus’s own research has been devoted mainly to these areas, especially associated with the early sixteenth-century iconoclast, Paracelsus. Most notably, in The English Paracelsians (London, Olbourne,1965) and The French Paracelsians: The Chemical Challenge to Medical and Scientific Traditions in Early Modern France (Cambridge University Press, 1991), Debus traced the ascendancy of a chemical view of nature that was very different from the mathematical and mechanical view associated with astronomy and physics but which, he has argued, was as significant at the time as the canonic one.

In this book, Debus concentrates on the rise of and debates over Paracelsian-based “chemical medicine” from the time of Paracelsus to the middle of the eighteenth century. Although Paracelsus published little in his lifetime and his collected works did not appear until close to the end of the sixteenth century, debates were already taking place in the 1570s, and medical debates became intense after 1600. For roughly the first half of the seventeenth century, these debates were between Paracelsians and Galenists.

However, by the second half of the century, it was no longer possible to speak simply of “Paracelsian” chemical medicine, due to the work of Jean Baptiste van Helmont (published in 1648), and its extension by others like Franciscus de la Boe (Sylvius) in his acid-alkali theory of digestion and Thomas Willis, who espoused theories of chemical “fermentations” as the cause of both physiological processes and disease. Moreover, the opponents gradually changed from Galenists to Mechanists, such as Giovanni Alfonso Borelli, Lorenzo Bellini, Georgio Baglivi, and Archibald Pitcairne.

In the first chapter, Debus gives a remarkable distillation (pun intended) of Paracelsian medical doctrine. Its viewpoint was iconoclastic: traditional academic Greek/Arabic medicine was both un-Christian and wrong; it had to be replaced by a new chemical medicine based on the twin pillars of Scripture and Nature. Its salient principles were a belief in macrocosmic/microcosmic chemical analogies with associated correspondences, a vitalist view of nature (both macrocosm and microcosm), a new set of chemical elements, the tria prima of salt, sulfur and mercury, a localized (and chemical) theory of disease (contrasting to Hippocratic/Galenist humoral theory), and a medical therapy based on the notion that like cures like, rather than the traditional cure by opposites. The medicines that the Paracelsians advocated were mineral and metal compounds in place of the predominantly plant-based Galenist pharmacopoeia.

Van Helmont came to exert the dominant influence on chemical medicine during the seventeenth century. Debus delineates in considerable detail both the developments in chemical medicine and the debates between its adherents and opponents. The story is carried into the eighteenth century, with brief accounts of the medical theories of the two most celebrated chemists of the early eighteenth century: Hermann Boerhaave and Georg Ernst Stahl. Interestingly, despite their chemical celebrity, neither was a supporter of chemical medicine; for totally different reasons (Boerhaave was a medical mechanist; Stahl a medical animist), neither saw more than a peripheral place for chemistry in medicine. Debus takes...