The August issue of La Recherche has the theme of ‘controversies in science’. I wrote several pieces for it – this is the first, on the battle between the Galenists and Paracelsians in the French court in the early 17th century.
“I am different”, the sixteenth-century Swiss alchemist and physician Paracelsus once wrote, adding “let this not upset you”. But he upset almost everyone who came into contact with him and his ideas, and his vision of science and medicine continued to spark dispute for at least a hundred years after his death in 1541. For Paracelsus wanted to pull up by its roots the entire system of medicine and natural philosophy that originated with the ancient Greeks – particularly Aristotle – and replace it with a system that seemed to many to have more in common with the practices of mountebanks and peasant healers.
Paracelsus – whose splendid full name was Philip Theophrastus Aureolus Bombastus von Hohenheim – had a haphazard career as a doctor, mostly in the German territories but also in Italy, France and, if his own accounts can be believed, as far afield as Sweden, Russia and Egypt. Born in the Swiss village of Einsiedeln, near Zurich, into a noble Swabian family fallen on hard times, he trained in medicine in the German universities and Ferrara in Italy before wandering throughout Europe offering his services. He attended kings and treated peasants, sometimes with a well-filled purse but more often penniless. Time and again his argumentative nature ruined his chances of a stable position: at one time town physician of Basle, he made himself so unpopular with the university faculty and the authorities that he had to flee under cover of darkness to avoid imprisonment.
Paracelsus could be said to have conceived of a Theory of Everything: a system that explained medicine and the human body, alchemy, astrology, religion and the fundamental structure of the cosmos. He provided one of the first versions of what science historians now call the ‘chemical philosophy’: a theory that makes chemical transformation the analogy for all processes. For Paracelsus, every natural phenomenon was essentially an alchemical process. The rising of moisture from the earth and its falling back as rain was the equivalent of distillation and condensation in the alchemist’s flask. Growth of plants and animals from seeds was a kind of alchemy too, and in fact even the Biblical creation of the world was basically an alchemical process: a separation of earth from water. This philosophy seems highly fanciful now, but it was nonetheless rational and mechanistic: it could ascribe natural and comprehensible causes to events.
Although Paracelsus was one of the most influential advocates of these ideas in the early Renaissance, they weren’t entirely his invention (although he characteristically exaggerated his originality). The chemical philosophy was rooted in the tradition known as Neoplatonism, derived from the teachings of Plato but shaped into a kind of mystical philosophy by the third-century Greek philosopher Plotinus. One of the central ideas of Neoplatonism is the correspondence between the macrocosm and the microcosm, so that events that occurred in the heavens and in the natural world have direct analogies within the human body – or with the processes conducted in an alchemist’s flasks and retorts. This correspondence provided the theoretical basis for a belief in astrology, although Paracelsus denied that our destiny is absolutely fixed by our horoscope. He proposed that the macro-micro correspondence led to ‘signatures’ in nature which revealed, for example, the medical uses of plants: those shaped like a kidney could treat renal complaints. These signatures were signs left by God to guide the physician towards the proper use of herbal medicines. They exemplify the symbolic character of the chemical philosophy, which was based on such analogies of form and appearance.
What the chemical philosophy implied for medicine conflicted with the tradition taught to physicians at the universities, which drew on ideas from antiquity, particularly those attributed to the Greek philosopher Hippocrates and the Roman doctor Galen. This classical tradition asserted that our health is governed by four bodily fluids called humours: blood, phlegm, and black and yellow bile. Illness results from an imbalance of the humours, and the doctor’s task was to restore this balance – by drugs, diet or, commonly, by blood-letting.
Academic doctors in the Middle Ages adopted the humoral system as the theoretical basis of their work, but its connection to their working practices was generally rather tenuous. Often they prescribed drugs, made from herbs or minerals and sold by medieval pharmacists called apothecaries. Doctors charged high fees for their services, which only merchants and nobles could afford. They were eminent in society, and often dressed lavishly.
Paracelsus despised all of this. He did not share the doctors’ disdain of manual work, and he hated how they paraded their wealth. Worse still, he considered that the whole foundation of classical medicine, with its doctrine of humours, was mistaken. When he discovered at university that becoming a doctor of medicine was a matter of simply learning and memorizing the books of Galen and Avicenna, he was outraged. He insisted that it was only through experience, not through book-learning, that one could become a true healer.
By bringing an alchemical perspective to the study of life and medicine, Paracelsus helped to unify the sciences. Previously, alchemy had been about the transmutation of metals. But for Paracelsus, its principle purpose was to make medicines. Just as alchemists could mimic the natural transmutation of metals, so could they use alchemical medicines to bring about the natural process of healing. This was possible, in fact, because human biology was itself a kind of alchemy. In one of his most fertile ideas, Paracelsus asserted that there is an alchemist inside each one of us, a kind of principle that he called the archeus, which separates the good from the bad in the food and drink that we ingest. The archeus uses the good matter to make flesh and blood, and the bad is expelled as waste. Paracelsus devised a kind of bio-alchemy, the precursor to modern biochemistry, which indeed now regards nature as a superb chemist that takes molecules apart and puts them back together as the constituents of our cells.
Most of all, Paracelsus argued that medicine should involve the use of specific chemical drugs to treat specific ailments: it was a system of chemotherapy, which had little space for the general-purpose blood-letting treatments prescribed by the humoral theory. This Paracelsian, chemical approach to healing became known in the late sixteenth century as ‘iatrochemistry’, meaning the chemistry of medicine.
Paracelsus was able to publish relatively little of his writings while he was alive, but from around 1560 several publishers scoured Europe for his manuscripts and published compendia of Paracelsian medicine. Once in print, his ideas attracted adherents, and by the last decades of the century Paracelsian medicine was exciting furious debate between traditionalists and progressives. Iatrochemistry found a fairly receptive audience in England, but the disputes they provoked in France were bitter, especially among the conservative medical faculty of the University of Paris.
That differing reception was partly motivated by religion. Paracelsus belonged to no creed, but he was widely identified with the Reformation – he even compared himself to Martin Luther – and so his views found more sympathy from Protestants than Catholics. The religious tensions were especially acute in France when the Huguenot prince of Navarre was crowned Henri IV in 1589. Fears that Henri would create a Huguenot court seemed confirmed when the new king appointed the Swiss doctor Jean Ribit as his premier médicin, and summoned also two other Huguenot doctors with Paracelsian ideas, the Gascon Joseph Duchesne and another Genevan, Theodore Turquet de Mayerne.
In 1603 Jean Riolan, the head of the Paris medical faculty, published an attack on Mayerne and Duchesne, asserting the supremacy of the medicine of Hippocrates and Galen. Although these two Paracelsians sought to defend themselves, they only secured a retraction of this damning charge by agreeing to practice medicine according to the rules of the classical authorities.
But the Paracelsians struck back. Around 1604, Ribit and Mayerne helped a fellow Huguenot and iatrochemist named Jean Béguin set up a pharmaceutical laboratory in Paris to promote chemical medicine. In 1610 Béguin published a textbook laying out the principles of iatrochemistry in a clear, straightforward manner free from the convoluted style and fanciful jargon used by Paracelsus. When this Latin text was translated into French five years later as Les elemens de chymie, it served much the same propagandizing role as Antoine Lavoisier’s Traité élémentaire de chemie did for Lavoisier’s own system of chemistry at the end of the eighteenth century.
But the war between the Galenists and the Paracelsians raged well into the seventeenth century. Things looked bad for the radicals when Henri IV, who had been prevented in 1609 from making Mayerne his new premier médicin, was assassinated the following year. Lacking royal protection, Mayerne took up an earlier offer from James I of England and fled there, where he flourished.
Yet when Riolan’s equally conservative son (also Jean) drew up plans for a royal herb garden in 1618, he did not anticipate that this institution would finally be established 20 years later as the Jardin du Roi by the iatrochemist Gui de la Brosse. In 1647 the Jardin appointed the first French professor of chemistry, a Scotsman named William Davidson, who was an ardent Paracelsian.
Most offensive of all to the Paris medical faculty was Davidson’s support for the medical use of antimony. Ever since the start of the century, Paracelsians and Galenists had been split over whether antimony was a cure or poison (it is in fact quite toxic). Davidson’s claim that “there is no more lofty medicine under heaven” so enraged the faculty that they hounded him from his post in 1651, when the younger Riolan republished his father’s condemnation of Duchense and Mayerne.
Yet it was all too late for the Galenists, for the Jardin du Roi, which became one of the most influential institutions in French chemistry and medicine, continued to support iatrochemistry. The professors there produced a string of successful chemical textbooks, most famously that of Nicolas Lemery, called Cours de chimie, in 1675. These men were sober, practical individuals who helped to strip iatrochemistry of its Paracelsian fantasies and outlandish jargon. They placed chemical medicine, and chemistry itself, on a sound footing, paving the way to Lavoisier’s triumphs.
What was this long and bitter dispute really about? Partly, of course, it was a power struggle: over who had the king’s ear, but also who should dictate the practice (and thus reap the financial rewards) of medicine. But it would be too easy to cast Riolan and his colleagues as outdated reactionaries. After all, they were right about antimony (if for the wrong reasons) – and they were right too to criticize some of the wild excesses of Paracelsus’s ideas. Their opposition forced the iatrochemists to prune those ideas, sorting the good from the bad. Besides, since no kind of medicine was terribly effective in those days, there wasn’t much empirical justification for throwing out the old ways. The dispute is a reminder that introducing new scientific ideas may depend as much on the power of good rhetoric as on the evidence itself. And it shows that in the end a good argument can leave science healthier.