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Turning Herbs into Drugs in the Middle Ages

Updated: Aug 30, 2023

We here at Points are delighted to welcome a new guest blogger for the next few weeks: Winston Black, an intellectual historian of medieval England and France who has published several essays on medical and religious education, and an edition, translation, and study of Henry of Huntingdon’s Anglicanus Ortus: A Verse Herbal of the Twelfth Century (Toronto and Oxford, 2012). He is currently the Haslam Postdoctoral Fellow in the Marco Institute for Medieval and Renaissance Studies of the University of Tennessee.

A recent essay in The Guardian compares modern cough medicines to the medieval cure-all theriac. The picture painted of medieval medicine is not so patronizing as usually found in the press: according to the author, neither ‘drug’ actually cures anything, there was a vigorous market for both, and both possessed some sort of placebo effect. The similarities end there. Whereas most modern cough medicines rely on sweeteners, affordability, and easy access for their appeal, the lure of theriac lay in its exotic, even repulsive content (viper’s flesh as the main ingredient), its cost (exorbitant), and the supposed difficulty in preparing it. Arnald de Villanova, a professor at the medical school of Montpellier around 1300, wrote an entire treatise on the topic, “On the dosage of theriac medicines” (De dosi tyriacalium medicinarum).

A copy of the “Tacuinum sanitatis” (‘Tables of Health’) from Vienna, ca. 1400, uses a well-stocked apothecary shop to illustrate the description of triacha, theriac.

Theriac is frequently held up as the medieval drug par excellence, and it probably was by the fourteenth century, but there were centuries of drug therapy before theriac was rediscovered. There was, in fact, an intellectual and economic gulf between the herbal pharmacy of much of the Middle Ages and the mature drug culture of the Later Middle Ages. How did this change occur? How did herbs become ‘drugs’?

Albarello vase for theriac; Italy, 1641.

There are several problems in discussing medieval drugs. The main problem is one of definition. The word ‘drug’ was not used until the very end of the Middle Ages to refer to medicine (droge meant ‘supply’ or ‘barrel’). Moreover, most of the substances we call ‘drugs’ didn’t exist or were rarely used then, such as refined or synthesized chemical compounds, legal stimulants like caffeine or nicotine, or illegal recreational drugs derived from marijuana or opium poppies. But if we use ‘drug’ in the broadest sense not as a substance that has by its nature a medicinal or intoxicating effect on an organism but rather as one that the user or provider thought would have such effects, this allows us to consider as ‘drugs’ a huge range of natural substances used in medieval medicine. For God, in a popular medieval view, provided the entire world for the benefit of mankind, and drugs could therefore be found everywhere, potentially in any animal, vegetable, or mineral.

I am opting, like a good medieval philosopher, to follow the mean between these views: the medieval drugs I am discussing are not modern pharmaceuticals, nor do they encompass every substance employed medicinally in the Middle Ages. ‘Drugs’ had to be invented, and this was a gradual process in the High and Later Middle Ages (ca. 1100-1400). They are not only substances, but are a complex of ideas and social markers. This is not the story of the introduction and employment of new substances, as with the Columbian Exchange of the sixteenth century, but rather of a shift in perspective about one’s relationship with nature and the sources of healing.

Early Medieval pharmacy was passed down in herbals recording the properties of single ingredients. From an 11th-century manuscript of the “Herbarium of Pseudo-Apuleius” (4th century); Oxford, Bodleian Library, MS Bodley 130, fol. 50v: Lily and Spurge.

Medieval pharmacy until the twelfth century was based on ‘simples’, single ingredients (herbs, spices, stones, animal parts) whose properties could be learned through apprenticeship or, for the literate, from a ancient and early medieval herbals, like the seventh-century Alphabet of Galen. Recipes survive which call for multiple ingredients, but most cures were dependent on these simples, usually from local plants, well known and easily obtained.

What was new after ca. 1100 was the notion that a natural substance could be, and in fact should be, identified, collected, studied, modified, measured, and administered by professionals trained in the art of medicine or, later, pharmacy. The ingredients of drugs were still found in nature, like the old materia medica, but patients, physicians, and pharmacists came to expect these natural substances to be unlocked, and their secrets to be compounded, inhaled, applied, or injected for the purposes of healing or intoxication. This change in attitude can be seen in antidotaries, pharmaceutical texts providing recipes for compound medicines like theriac, which became popular after 1100, overshadowing though not replacing simple herbals in the Later Middle Ages.

Many intellectual and cultural movements, particularly after the eleventh century, contributed to this shift in perspective, not the least being contact with Islamic societies during the Crusades (1095-1291), a growing emphasis by Church leaders on not just orthodox practice but also a certain level of understanding of doctrine among all Christians, as well as rising literacy and numeracy, and increased urbanization and long-distrance trade. But I wish to highlight three particular aspects of High Medieval culture that contributed to the invention of ‘drugs’: individualism, exoticism, and scholasticism. Or to put it more simply, unburdened by vague –isms: some plants are ‘drugs’ because they have to be compounded, dosed, and prescribed specifically for me; some plants are drugs because they come from far away or are hard to keep and prepare; some plants are drugs because it takes a natural philosopher to understand the correct quantity and quality of ingredients in a medicine. These three ideas would come to dominate the drug culture of Later Medieval Europe, at least among the wealthier, urbanized parts of society.

Faced with an embarrassment of riches, Henry felt obliged to explain (in a poem on comfrey, Symphytum officinale) why there were so many herbs with overlapping, and apparently redundant, effects. This seemed to him superfluous, which was impossible in his understanding of the divinely planned, beneficial universe. God does nothing in vain, and every product of Nature is informed by divine providence:

Some people question why He who granted every good [i.e. God] would give the same power to so many herbs. I will forbid them to be in doubt, since there are four humours and four things will affect them: moisture, cold, heat, and dryness rule over bodies in varied ways. For now one alone holds dominion over them, now one or the other reigns, now three joined together at once. But if those four should wish to rule now as one, unexpected death arrives. Therefore, when varied bodies agree in these ways, this medicine was effective for me, none will be effective for you, that one was good for you, you’ll see this one is good for me. Many causes are attributed to the same disease, because herbs differ according to different bodies.

The rational system underlying this poem, known as the humoral theory or humoralism, was pieced together by Muslim and Christian philosophers from their readings of ancient medical writings by Hippocrates and Galen. Humoralism is the belief that health was dictated by the relative balance of four bodily humors: blood, phlegm, yellow bile, and black bile. Each of the humors could increase, decrease, or change quality according to the relative strength of the four elemental qualities (hot, wet, cold, and dry) of one’s environment, activity, food, drugs, or emotions. Humoral theory could, and did, get far more complex in the Later Middle Ages, but it would remain the basis of most pathology and pharmacology until the eighteenth century in some medical schools.

In his explanation of the apparent redundancy of drugs around the world, Henry brought to bear the elements of humoral medicine (humors and qualities), as well as a conviction that every person has individual medical needs. The imbalance of qualities specific to an individual body required a specific drug or combination of drugs. The juxtaposition of these ideas, old and new, helps explain why “this medicine was effective for me, none will be effective for you, / that one was good for you, you’ll see this one is good for me.”

This illumination of ca. 1325 from an antidotary called “Circa instans” shows a customer inquiring about a drug from a pharmacist. No natural substances are shown, and drugs have been confined to a series of jars. London, British Library, ms Sloane 1977, fol 49v.

Henry’s poem is representative of a new set of attitudes in twelfth-century Europe that helped turn herbs into ‘drugs’, and made possible a medical outlook in which compound medicines like theriac, composed of viper’s flesh and 60 other ingredients, could be effectively marketed. Mere herbs could be found and prepared by anyone with a little training. Drugs, though, are the product of long learning, skill, and experience. And even when the drugs are still ‘simples’, like those described in the Anglicanus ortus, they were increasingly subjected to a more rigorously rationalized pharmacology, and exotic substances were privileged over local flora. In my next post I will look at this last process, the localization of drugs in increasingly distant sources, from the fields to formal gardens, from Arabia to Paradise.


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