Shortly after AD 754, a bishop in Anglo-Saxon England wrote to his friend, Lull, the bishop of Mainz in Germany, asking to be remembered, should Lull acquire any new books on the secular sciences, including medicine. Bishop Cyneheard of Winchester was concerned to get new information not just for its own sake, but also in the hope that it would resolve a pressing problem. The foreign ingredients prescribed in the books he did have were unknown and difficult to obtain, and it was possible, he imagined, that new books, written specifically for a modern, Northern European audience, would emphasise more local herbs and substances. Cyneheard was not exaggerating. The lists of drugs found in Anglo-Saxon recipes include balsam, cassia, cinnamon, aloes, ginger, incense, pepper and mercury, all of which required being brought from Spain, Africa, Arabia, the Near East or even further afield. But come they did. Some became sufficiently common that their name was translated into English: Chian mastic became ‘hwitcwudu’, ‘white chewy stuff’. Others remained rarities. Another of the Anglo-Saxon missionaries in Germany, Willibald, later St. Willibald, had no scruples about smuggling some extremely rare balsam through customs control on his departure from Tyre.¹

These stories from Northern Europe remind us that medicinal substances have always played a major role in the interchange between cultures from our earliest records. Ancient Egypt was viewed by the Greeks as a veritable paradise of drugs – I use the word paradise deliberately here for this word for gardens is a Persian word taken over by the Greeks and then the Romans, and thence into many West European languages. From the Homeric poems onwards, Egypt is credited with a major role in supplying healing substances, and the discoveries of archaeology have only confirmed the long existence of a drug trade. The Mycenean tablets include spices coming from Egypt, and recent excavations on Crete in the Mycenean period have uncovered what may have been a sort of pharmacist’s workshop that used minerals found in Egypt.² The Egyptians in their turn imported substances from Greece, although admittedly in fewer quantities than they exported. A similar story of commercial interchange is revealed by the cuneiform tablets of the Near East.³

As our evidence grows in quantity from the fifth century BC onwards in Greek, and from the third century BC in Latin, this pattern of the cultural transfer of drugs becomes ever more apparent and ever more extensive. From some 250 plants mentioned in medical texts around 400 BC, the number had risen to around 700 by AD 200, and was to continue rising.⁴ There were local traditions of pharmacology. North Western Europe has produced hundreds of so-called oculists’ stamps from the Roman period, designed to imprint on sticks of eye ointment, collyria, the name of the drug, its inventor, and the condition for which it was thought appropriate.⁵ Some of their authors have Celtic names, others Latin, others Greek. At the other end of the Roman Empire, we have a price list of drugs available at Coptos on the Nile, the entrepôt where rare materials that had been transported overland from ports on the Red Sea were put on board boats for their journey down the Nile to Alexandria, and vice versa. This fragmentary list mentions cinnamon, saffron, mastich, aloe, balsam, amomum, and asphalt.⁶ We no longer need believe in J. Innes Miller’s romantic vision of fleets of intrepid traders sailing to E. Africa, or the Moluccas or even further afield in dhows and outriggers in search of rare drugs paid for by streams of imperial gold. The more prosaic evidence of papyri, coin-hoards and excavations has shown a much more stable and a much more reduced pattern of small shipments of high value substances. Alexandria was the focal point of the trade, for drugs could reach there via the Nile, the Mediterranean or by camel train across the desert.⁷ The ambitious and wealthy young Galen, returning from his studies at Alexandria, bought up the drugs that he encountered being transported by a desert caravan from the borders of India. From Crete, a veritable garden of Eden for botanical drugs, agents of the Roman emperors arranged for baskets of herbs to be sent to Rome, and other merchants joined in this lucrative trade. Galen, our informant, warns his readers to beware of the tricks of the drug-sellers – filling the baskets with more than their usual quantity of earth, stuffing stems with sweet smelling gum to retard or disguise the inevitable process of decay, or simply blinding prospective purchasers with science as they passed off inferior substitutes for the real thing.⁸

The movement of substances was largely from East to West – we hear of few Spanish plants, for instance – and outwards from the Mediterranean. Plants from Northern Europe are hardly mentioned in our mainly Greek sources, and we have no southern equivalent of the doctor from Late Roman Gaul, Marcellus of Bordeaux, who combined drugs from the South with others of a more local origin. Marcellus, like the Roman Pliny the Elder three centuries before him, was faced with a problem, namely that of language: how to make sense of the names of plants known only through a foreign language – in this case Greek. There were various solutions, transliteration, translation, or some combination of the two. Some writers produced lists of synonyms of plant names. One of them was Pamphilus, a Greek of the first century AD, whose names for plants in Greek, Latin, Hebrew, Dacian and Egyptian can be found in the margins of our oldest manuscript of the most famous Greek herbal, that of Dioscorides, and also in Latin in the late-antique herbal of Apuleius. Galen snootily disapproved: ‘Pamphilus is like a herald calling out the names of runaway slaves, yet who wouldn’t recognise them if they stood in front of him.’ But for many doctors, these lists of synonyms would have been extremely valuable, even if they never found the opportunity to use recipes in Berber, Persian or other more exotic tongues for which these dictionaries apparently offered a guide.Reference Wellmann⁹

Names also imply identification, knowing what plant is what, and, in another genre of pharmacological writing that survives from Antiquity, knowing what drug can be substituted for another, for, as Galen emphasized, some drugs were unobtainable locally or were beyond the pocket of patients and practitioners. We may commend his public-spiritedness in providing poorer colleagues with rare drugs and advice on substitution – but one should also note the passages in which he instructed his colleagues how to add expensive but pharmacologically useless preparations to push up the cost of drugs for the rich, who, he alleged, would sneer at a drug that was effective but cheap. Bulked out and elevated in price, it became for them much more acceptable.

Plant identification presented enormous problems. We hear of the special skills of rhizotomoi, rootcutters, whose expertise was often considered superior to that of doctors. Our earliest surviving Greek writer on botany, Theophrastus, the pupil of Aristotle, derived much of his information from talking with these men (and, often, women), and several famous doctors wrote books entitled ‘Root-cutting’, Rhizotomikon.¹⁰ Until the second century BC, it would appear that descriptions of plants were purely verbal, and, even after they had been introduced to aid identification, illustrated tracts will have been beyond the pocket of most doctors. The most famous illuminated manuscript on herbs, the Vienna codex of Dioscorides, was painted around AD 512 for a Byzantine princess, and many of its descendants have been located in similarly wealthy, and perhaps non-medical, collections – a passion for plants and for beautiful paintings is not confined, even today, to the medical profession.¹¹

Dioscorides’ treatise, its organisation, and its illustrations, became the bible of medical botany for centuries.¹² He himself was a Greek from what is now Anazarba in Southern Turkey. He studied at Tarsus, spent some time in the Roman army, and wrote his treatise on Materia medica around AD 67.¹³ He includes a succinct description of over a thousand substances, around 700 of which are plants. His book is a masterpiece of clarity and concision, first describing each plant or animal, and then listing its properties. Most of his plants come from the Eastern Mediterranean, but others come from as far afield as India and East Africa. This book quickly gained canonical status, and was praised highly by Galen. It was subsequently translated into Syriac, Arabic, Latin and a multitude of vernacular languages down to the seventeenth century. But it has two drawbacks. First, it is a study of materia medica: it is not a collection of recipes. Galen, for example, whose drug books cover almost 2000 pages, takes relatively little from Dioscorides. He prefers instead to copy out large sections from the works of five or six earlier pharmacologists. One of them was the much-travelled Statilius Criton, doctor to the emperor Trajan and our most informative source about one of the lost best-sellers of Antiquity, Cleopatra’s Guide to Beauty, her Cosmetics.¹⁴ (Like many modern successors, this work was not written by its purported author.)

However, the major problem with Dioscorides’ book was its organisation. In his preface he stresses that he lists his substances according to their general properties, diuretics, astringents, etc, for, he claims, a doctor seeking an appropriate drug for his patient wants to find a passage with a cure, not to have to scroll through many different and irrelevant drugs before he finds the required information.Reference Scarborough and Nutton¹⁵ (In Dioscorides’ time books were still copied in scroll form, and finding a relevant place was not easy. It may be no coincidence that the earliest surviving detailed list of contents and chapter numbers comes from the Drug book of Scribonius Largus, written 20 years or so earlier than Dioscorides.) But others found Dioscorides’ organisation complex and unnecessary: by AD 500 at least one recension of Dioscorides’ book was in circulation in which the drugs were listed in alphabetical order – the Vienna Dioscorides is a manuscript of this type, and an alphabetical version in Latin was in circulation by AD 600.

Dioscorides’ book became one of the templates for subsequent pharmacology, and deservedly so. But his emphasis on drug properties, faculties or potentialities – the Greek word is δύvαμις, dynamis, from which we get dynamics and dynamite – raises a further question of great significance for later developments. How do drugs work, and how can that be explained in a way that distinguishes the true pharmacologist from the mere empiric proceeding by trial and error? Dioscorides focused on drugs with similar powers of action, but that did not satisfy everyone, particularly if they happened to use different explanations for illness. That a drug had the property of easing urination, for example, said little about how it worked, if difficult urination were merely a symptom of something deeper – indeed, simply removing the symptom might be dangerous if it meant that more serious considerations were neglected.

This was the problem raised at length by Galen (129–c. 216) in a typical blend of genius and over-optimism. If, as he and his fellow Hippocratics argued, all disease is something individual, manifesting itself in different ways according to the specific bodily, humoural balance of the individual, the ideal physician needs to diagnose and prescribe drugs that fit the individual patient in order to restore the body’s natural balance. But how? That was the question Galen set himself to resolve. One way, he suggested, was to relate the intensity of drug action to the intensity of the disease. The latter, he thought, could be easily judged by a competent physician familiar with his patient – we might smile at the optimism of an ancient doctor working without any of our modern diagnostic aids, save perhaps for an occasional water clock for measuring pulse beats – and what was necessary was to determine where on the scale of intensity to place a particular drug. Armed with this knowledge, one could then tailor the prescription to the individual patient and the individual illness.

Galen suggested – or perhaps developed – a notion of grades, four major categories, ranging from the powerful to the weak, each subdivided into three divisions. At the one end were drugs, such as caustics or some poisons, so powerful that, unmixed, they caused death within minutes: at the other, were drugs whose effect was absolutely imperceptible to the senses, yet whose presence in a compound remedy could just tip the balance and create the right action. All drugs, Galen argued, worked by moderating the body’s four humours in four ways – cooling, heating, drying, and moistening – corresponding to the Aristotelian notions of qualitative change, which allowed Galen to interpret Dioscorides’ ‘potentialities’ in an Aristotelian way. By using such a scale, Galen believed that one could attain a greater certainty of cure, a laudable objective that for a variety of reasons defied attainment.¹⁶

Some reasons relate to Galen’s own inconsistencies. He never succeeded in grading disease consistently, and, indeed, talks at different times of 15 grades of disease intensity, not 12. Secondly, this hypothesis remained for many plant drugs just that – a hypothesis, for he himself allotted grades of intense action only to 161 out of 475 drugs. Thirdly, his explanation presupposed an Aristotelian/Hippocratic medical universe. Those, like the ancient followers of Asclepiades and Thessalus, who favoured a more mechanistic, and a more atomistic, understanding of the body found an explanation in terms of qualities superfluous or irrelevant. But, at least until the 16th century, humoural medicine dominated, and this problem was pushed to one side.

Potentially more fatal to this theory was the realisation that there were many proven examples of drugs that did not seem to act in the way Galen had predicted. The belief that a substance worked in a particular way, to heat or cool, for instance, might well be valid for it on its own, as a simple drug. But often, particularly in compounds, the observed effects did not correspond to what might have been predicted if one added all the grades together. As in cookery, the quality of the result might not always reflect what was known of the ingredients. So it was with drugs, and hence Galen explained that the effectiveness of some drugs in a particular instance was due to their ‘total substance’, the way in which the combination of qualities mixed together. Changing the formula in any way would therefore damage its potential effectiveness. The notion of drugs of total substance, involving a specific and unknown (later Latin authors used the word ‘occult’) mixture of qualities, threatened the whole theory, for it allied the Galenic practitioner with the empiric, skilled in applying drugs that worked, but without knowing why. It was also a challenge, for the more that could be known about such combinations, the less they would be categorised as ‘occult’, and the more, it was believed, they would justify the theory of humours.

By AD 250 the broad guidelines for the future development of pharmacology had been laid down, and were being widely followed, particularly in the Greek world of the Eastern Mediterranean. Galenism progressively triumphed there, driving out all learned alternatives by AD 500, and migrating into the vernacular language of the Middle East, Syriac. It offered to its adherents two complementary models for understanding pharmacology. One, that of Dioscorides, looked for medical plants and animals and described their effects: the other was Galen’s scheme of grades of drug action. Both models offered possibilities for further development. Access to new lands brought new opportunities for finding unknown or unfamiliar substances, whose properties could be carefully assessed and categorised. Galen’s avowed failure to follow up his own suggestions – a failure for which one can blame his advanced years as much as a lack of enthusiasm – and his theoretical inconsistencies challenged his followers to do better. In so doing, they were not overthrowing Galenism, but strengthening its foundations. They were turning pharmacology into a true scientia, a firmly founded intellectual system of knowledge.