The Universals and Particulars of Poison in the Sixteenth Century

[Revised from a presentation at the History of Science Society 2015 meeting in San Francisco]

Physicians since the late thirteenth century vigorously debated the theoretical and practical differences between medicine and poison. It was an effort fueled by the natural and well-known dangers of many medicinal substances.

Over the course of the sixteenth century, however, physicians fundamentally reframed their debates about the nature of poison and formulated new ways of discussing it in specific medical / toxicological literature dedicated to poison (venenum).

Sixteenth-century physicians writing about poison focused their attention not on philosophical distinctions between medicine and poison, but rather on the conditions under which something might be considered a poison—the particulars of poison, we might say. This attention to particulars of course parallels developments in anatomy, physiology, botany, natural history, and numerous other burgeoning fields at early modern universities and broader intellectual social networks as well.

Today, I hope to illustrate how physicians writing about poison came to argue that it was impossible to understand poison as either a universal or particular phenomenon without accounting for both perspectives simultaneously. Consequently, physicians reshaped their medical and toxicological works to reflect this multi-faceted view of poison by crafting a new concept of venenum defined dually: one axiomatically by its universal ability to harm the human body (and thus curable through universal remedies); the other by emphasizing the particular classes, properties, natures of various poisons.

In order to provide some necessary context for these 16th cen. developments, I’d like to like to begin with a brief history of premodern toxicology and poison literature even if it can be no more than a whistle-stop tour of a few critical inflection points.

Needless to say, physicians have always been interested in dangerous drugs, treating bites of venomous animals and accidental ingestion of poisonous substances. The nature of classical toxicology was remarkable in its systemization of dangerous plant, animal, and mineral substances (Nicander, Dioscorides, Pliny, Galen to same some of the most broadly known). But classical toxicology did not, however, significantly address the nature of poison or venom itself. The nature of pharmakon easily ranged over a wide spectrum of action, from imperceptible affects to violent death. To question whether something should be labeled as a drug or a poison simply didn’t make much sense.

Avicenna (fl. 11th cen.), the great Arabic medico-philosopher–whose medical encyclopedia (the ) became foundational for medicine in the Latin West–remarked in a comparatively small section, somewhat buried within the Canon that poison, as opposed to food or drugs, could be defined by its “specific form” or “total substance” [latin terms]. This move was instrumental in focusing later attention of physicians of the Latin West on poison as a separate category of substance, distinct from food or medicine. In a way, it was this formulation that 16th century physicians were trying to refute.

In the 2nd half of the 13th century in Montpellier, physicians such as Arnau of Villanova and at Paris, Jean de Saint Amand began to inquire about the nature of theriac. Exactly how does it get its remarkable power against poison? How should it be used? Given its affinity or similitude or antipathy to poison, can it be administered to a healthy body? Or would it act as a poison in itself if it didn’t have a poison to react against? If it’s a poison, or potentially dangerous, what is the proper dose? These discussions were not about poison per se, but they obviously flirted with the topic and began to outline the various philosophical issues at stake—namely WHAT IS POISON?

A direct answer to that question comes from Pietro d’Abano (d. c. 1316), well known as the Conciliator for his monumental work that tries to reconcile some points of apparent conflict between Aristotelian philosophy with Galenic medicine. Perhaps even more widely circulated than his Conciliator was his treatise on poison and their remedies (De venenis). As had been done before in a variety of contexts, he provided a course a list of dangerous substances, their signs, and remedies.

More significantly, however, the reason that Pietro’s text was well known and well cited can be traced to a few key features:

  1. consolidate Avicenna’s sections on poison into one text (on powers of food and drink generally; medical condition of poisoning)
  2. foreground the natural philosophy of poison and differences between poisons
  3. most significantly: writing a standalone text on poison that takes poison itself as the object of inquiry.

Other physicians in the later 14th century further developed the genre, incorporating into treatises on poison sections of “problems,” clearly reflecting the problemata literature growing in popularity. Poison posed new natural philosophical questions with implications for toxicology and the relationship between poison and disease. In this genre of medical literature on poison of the 15th century, we see new attention to poisonous properties, nature of poisoned bodies. For instance, whether it is possible to be nourished by poison (not a new question), became the subject of more sophisticated analysis that resulted from a more nuanced discussion of poison itself.

Finally, to the 16th century! Key points to summarize so far:

One of the clearly new features in poison texts was a linguistic concerns a result of medical humanism: pharmakon vs. venenum. A few examples: In the Greco-Latin version of Dioscorides’s De materia medica, first printed in Florence in 1518, for instance, the Florentine humanist Marcello Vergilio Adriani (1464 - 1521) lamented the difficulty of translating pharmakon, “which the Greeks used indistinctly for speaking of both helpful medicines and of lethal poisons, but for which the Latin language has not provided the equivalent to suggest the double meaning.”

The well known physician Girolamo Mercuriale (1530 – 1606), who held professorships at Padua, Bologna, and Pisa, described in a treatise on the compositions of medicines how pharmacum meant three different things to physicians: either poison (venenum), pigment (pigmentum), by which women color their faces, or medicine (medicina), which maintains health. He noted that while the Greeks divided poisons into corruptive modes and lethal modes (in other words, dangerous versus deadly medicines), his contemporaries are “now used to grouping all poisons under a common name.”

So we have an interesting tension here. I’ll give more specific examples in a moment, but want to restate the larger point first.

Partially as a result of the linguistic and conceptual tension between pharmakon and venenum, partly because of the expanding natural world, physicians endeavored to understand the concept of poison in the larger order of nature and an ever-increasing number of medicinal substances.

At the same time, somewhat contrary to the notion of a humanist focus on particulars, notions of poison were shaped equally by the idea of poison as a universal—the idea of some kind of either material substance or spiritual essence that was fundamentally opposed to the human body—either the heart , the vital spirit, or innate heat.

This universal notion of poison not merely a scholastic, textual holdover. Physicians also had employed (to various extents) the notion of venenum as a cause of disease. This was noticeable first to explain the cause and nature of pestilential disease in the fourteenth century, and especially, and with new vigor in the sixteenth century, when physicians such as Paracelsus, Fernel, and others emphasized poison as a cause of disease in general. This association with disease, of course, implicitly defined poison as a kind substance universally harmful to the human body.

Physicians thus forged a new conception of venenum–and quite significantly in my view–a new approach to toxicology. Their approach simultaneously embraced the broad range of actions inherent in dangerous drugs AND inscribed them with a more specific and standard vocabulary for describing particular effects of kinds of deleterious substances. Poison needed to be understood BOTH by its universals and particulars.

A few quick examples to illustrate:

Girolamo Cardano (1501-1576)

The famous Paduan physician Girolamo Cardano (1501-1576) applied his wide-ranging interests and erudition to topics ranging from algebra through astrology to moral philosophy. Cardano’s universal definition of venenum deliberately encompassed many particular kinds of poisons, effectively serving as an umbrella for the many varieties of poisons, ways they affected the body, and processes of poisoning. He expressly wanted to move from the general to the particular, especially in terms of the modes by which poison could operate based on, as he put it, reason, experience, and authority. Cardano expressed the necessity for physicians to understand the individual natures of a wide spectrum of poisons, not just for theoretical, but for practical applications, for “although it is with the greatest difficulty, it is necessary for a physician to know poisons and their circumstances, including their manner [of action], strength, species, and quality, if he wants to treat correctly.”

Cardano stressed the physical qualities of poison that made it poisonous rather than simply harmful, similar to but different from the “specific form” that previous authors typically employed in their works on poison. It was some kind of delicate substance—not merely an occult quality—that could turn a harmful medicine into a poison. Cardano’s primary approach to differentiating poison stemmed from the ways they introduce harm into the body, such as through air, water, food, etc and eve spells (he was careful to point out that some of these required a substrate, while others did not).

His focus on the movement of poison set the stage for his more elaborate analysis on the relationship between poison and putrefaction. For Cardano, the kind and severity of disease was determined by the level of perfection that the putrefaction process obtains. It was in fact according to various corruptive processes rather than the traditional tripartite division of animal, vegetable, and mineral poisons that guided Cardano’s chapters on the many possible origins of poison, whether from putrefaction, corruption, from air, water, contagion, or by another poison. Cardano’s several long chapters on the nature of putrefaction and corruption certainly stand out as unique features for a text on poison. Although he does not say much about poison itself in these sections, his reasons for the apparent digressions soon become clear. Cardano, in order to explain range of effects of poison (that is, differentiating weak from strong poisons), wanted to establish the centrality of the role of putrefaction in generating poison and the kinds of disease that may arise from the various kinds and degrees of putrefaction.

Girolamo Mercuriale (1530 – 1606)

Another approach to refining the notion of poison comes via Girolamo Mercuriale, who composed his treatise De venenis et morbis venenosis (On Poisonous Diseases and Poisons) in 1584. Mercuriale was well-steeped in the medical and natural philosophical traditions of northern Italy, holding at various times professorships at Padua, Bologna, and Pisa. Mercuriale focused on reconciling ancient and contemporary definitions of poison, and seems to resurrect a classical notion of pharmakon as a basis for understanding venenum.

Mercuriale methodically advanced philosophical arguments about how poison must be understood in the larger order of nature, not only w/r/t the human body. He particularly emphasized the variety of ways that venenum must be understood. He remarked, for instance, that substances in general could be understood in two ways, one in consideration of the substance alone, another by considering its differences and qualities joined with it. Thus, he emphasized poison as a non-natural mixture (that is, part good and part bad), in contrast to naturals (always good) and preternaturals (always bad).

Even if Mercuriale embraced a more or less standard definition of poison, he emphasized the spectrum of harming potential of the great variety of so-called poisons: “although all poison by its nature harms and corrupts the nature of man, the difference [between particular poisons] is not small, since some never harm, even if they have the potential to do so, and other always do, but some slowly, others quickly.” He goes on to explain how some so-called poisons may not harm at all, depending on individual properties or if the body has been prepared ahead of time to withstand the poison, such as in the legendary tale of Mithridates, or if the poison is removed from the body quickly enough. His comparative approach helps him to outline the difference between venom and other poisonous substances, stating that the venom of venomous animals has a natural sympathy to itself, and thus can be used to extract poison from the body, whereas other poisons are more liable to injure the body.

Mercuriale, even more than Cardano, emphasized Aristotelian causality as the most useful way to understand poison, and his chapters on the material, efficient, and final causes of poison exemplify the prevailing Renaissance Aristotelianism. It was within this Aristotelian framework that Mercuriale focused on the physical interaction with poison and the body, including differences in speed, intensity, and ways in which such poisons either kill or injure. Regarding the material cause, he mentioned that the ancient philosophers Democritus (5th cen. BCE) and Lucretius (1st cen. BCE) had suggested that the material of poison was sharp and barbed (asperis & hamatis). He reported how this idea had been rejected in favor of a more Aristotelian approach that argued for a common and universal material, as well as an immediate and particular material: the common material was of course the four elements; the particular material was vapor, humor, or juice (succus), and a terrestrial component that was animal, plant, or mineral in nature.

Andrea Bacci (1524-1600)

The universal and particular natures of poison that derived from separating poison and venom features prominently in a different kind of text on poisons and antidotes by Andrea Bacci (1524-1600) from 1586. Bacci began to practice medicine in 1551, becoming a professor of botany at Rome in 1567; in 1587 he was installed as physician to Pope Sixtus V. His wide-ranging interests led him to compose texts across a diverse range of fields, including balneology, hydrology, oenology, toxicology, and pharmacology. Bacci did not propose any radically new conceptions of poison in his text De venenis et antidotis (On Poisons and Antidotes), though he canvased many of the same natural philosophical questions that preoccupied authors of earlier poison texts—an approach that might have developed from his correspondence with Cardano and Mercuriale.

Typical for later sixteenth-century treatises on poison, Bacci shied away from embracing an axiomatic definition of poison based on any particular definition or properties. He emphasized instead that poison should be understood as something’s opposite. As a result of this approach, he explicitly and repeatedly argued against the idea that poison should be considered as belonging to a single genus that can be defined as contrary to human nature.

Although Bacci endorsed an ontological existence of poison as antithetical to the body, he labored to argue that it should be considered as a natural substance, and that, despite how it had been discussed previously, poison was similar to other natural substances such as the magnet in the way that it seemed to have unusual powers. Of course comparisons between the magnet and poison had been made before, but Bacci makes the comparison to not just to evoke similarities of action by specific form or some occult property as had been done previously, but to minimize any unique ontology of poison: that even if we define a genus of substance called venenum and everyone agrees that it harms the human body by some universal definition, that does not make it, or its powers, fundamentally unique in nature. Therefore we can only understand it through its particulars.


Even though I’ve only mentioned a few highly selective, but i think representative, examples, I hope I’ve suggested how Sixteenth-century medical literature on poison informatively captures a productive tension between physicians’ interest in the universals and particulars of poison. In this way, it holds important implications for the development of toxicology. It would a bit a presentist to suggest this could be construed as something we might recognize as “modern toxicology” emerges at this time. But isn’t a bit boring to hear paper that doesn’t suggest anything provocative? So that’s exactly what I’ll suggest. This is NOT to say that toxicology–attention to harmful substances–is new in the 16th century. But rather that they placed an emphasis on the various nature of poisons ALONG WITH attention to the broader concept of toxicity—-a systematic exposition of fundamental processes of harm inside the human body, especially as relates to putrefaction and disease.

Even as the universal nature of poison persisted but was complicated by particulars, this held important implications for antidotes and cures for poisons. If you don’t have a singular poisonous power (through specific form or total substance), can you have a poison panacea like theriac? Of course we’ll hear much more on this topic in the following papers.