When the Black Death swept across Europe, people were desperate. Civic leaders passed laws, kings issued edicts, and the clergy prayed fervently. But nobody was more on the front lines of this terrifying pandemic than the medical practitioners of the day. From apothecaries mixing herbs to barber-surgeons setting bones and university-trained physicians diagnosing illnesses, everyone tried to understand and fight the pestilence.
What Doctors Believed: Health, Sickness, and the Body
The medical theories guiding doctors during the plague era weren’t new; they were ancient, stretching back to the giants of Greek and Roman medicine, with some extra layers added by Arab scholars. Think of it like this: the core operating system for medicine hadn’t had a major update in over a thousand years!
It all started with figures like Hippocrates (yes, the guy doctors still take an oath named after). Living around 460-380 BCE, he pushed for a rational approach. Forget magic and angry gods, he said; look at the patient, observe nature, study the environment, diet, and habits. He emphasized detailed case studies, tracking symptoms like temperature, skin color, urine quality, and breathing to understand a disease’s natural course and see what treatments actually worked. For Hippocrates, disease was natural, understandable, and predictable.
Building on earlier ideas, Hippocrates (or writers associated with him) popularized the theory of the Four Humors. This became the bedrock of medicine for centuries. The idea was that the body contained four key fluids (humors) corresponding to the four elements:
THE FOUR HUMORS AND THEIR CORRESPONDENCES
| Humor | Element | Organ | Season | Qualities | Character (Dominant Mood) | Planet |
| Blood | Air | Liver | Spring | Warm/Moist | Sanguine (optimistic) | Jupiter |
| Phlegm | Water | Brain/Lungs | Winter | Cold/Moist | Phlegmatic (calm) | Moon/Venus |
| Yellow Bile | Fire | Gallbladder | Summer | Warm/Dry | Choleric (irritable) | Sun/Mars |
| Black Bile | Earth | Spleen | Fall | Cold/Dry | Melancholic (sad) | Saturn |
Good health, according to this theory, was all about keeping these humors in balance. Too much or too little of one humor, and you’d get sick. Your body’s “heat” and “humidity” were crucial.
Then came Aristotle (384-322 BCE), the “master of those who would know.” Though more focused on how the body works (physiology and anatomy) than on healing, he cemented humoral theory as fact. He also championed a super logical, systematic way of thinking (scholasticism) that valued argument and established authorities (like himself!) over direct experience. This approach dominated medieval universities and influenced how doctors thought – sometimes leading them down wrong paths because the “authority” was incorrect.
Galen of Pergamum (130-201 CE) was the ultimate synthesizer. He took Hippocratic observation and Aristotelian philosophy and built a comprehensive medical system. He categorized factors influencing health into three groups:
- Naturals: The body’s internal state – the humors, elements, qualities, and their balance.
- Contra-naturals: The causes of imbalance – the disease itself and its symptoms (e.g., fever = excess “hot and moist” blood).
- Non-naturals: Six external factors you could (mostly) control: air quality, motion/rest, food/drink, sleep/waking, evacuation (getting rid of waste/excess humors, like through bleeding), and “affections of the soul” (your mood).
According to Galen, messing up the non-naturals (breathing bad air, eating wrong, not sleeping, getting scared) could throw your humors out of whack and cause disease. The cure? Adjusting these non-naturals (move to good air, change diet, get rest, controlled bleeding, soothing music). This Galenic framework was the model for medicine in Europe for almost two thousand years. As physician Arnau de Vilanova put it around 1300, Hippocrates and Galen gave medicine its rational form and showed how to apply it.
Arab scholars played a crucial role in preserving and expanding on Greek knowledge when Europe was in the so-called Dark Ages. Thinkers like Avicenna (Ibn Sina, 980-1037 CE) were incredibly influential. His massive Kanon of Medicine became a standard textbook in European universities for centuries after being translated into Latin.
One major – and debatable – contribution from the Islamic world (via the Roman-Egyptian astronomer Ptolemy) was firmly linking astrology to medicine. The idea was that planets and stars directly influenced the human body because they corresponded to the elements, humors, and qualities. Your birth chart mattered, but so did the current alignment of celestial bodies for deciding the best time for surgery, taking medicine, or starting a diet. This wasn’t seen as anti-religious; it was just another “non-natural,” hidden (“occult”) force influencing health. Many believed widespread epidemics like the Black Death were triggered by specific astrological events.
Becoming a Doctor in Plague Times
So, how did someone become one of these esteemed physicians? It was a long, formal process centered around universities.
Medical education in Western Europe really kicked off in places like Salerno in southern Italy, a melting pot of Latin, Byzantine, and Arab cultures. Scholars like Constantine the African translated crucial Greek and Islamic medical texts into Latin, forming the core library for centuries. This broke the clergy’s near-monopoly on medical knowledge; soon, physicians weren’t monks, and monks generally weren’t trained as physicians.
Famous medical schools sprang up: Montpellier in France (1180), Bologna in Italy (around 1260), Paris (1253), and later in northern Europe like Vienna (1399) and Cambridge (1423).
The path was rigorous. First, a boy (women weren’t allowed) attended Latin school to master the language of scholarship. Around age 14, he’d head to university for 4-5 years studying the seven liberal arts (grammar, rhetoric, logic, arithmetic, geometry, music, astronomy). Only after getting an arts degree could he enter medical school, which lasted another 4-5 years.
The medical curriculum was almost entirely based on the classics: Hippocrates, Galen, and Avicenna were the stars. Professors read directly from these authoritative texts, adding their own commentary, and students diligently copied it all down. It was about absorbing established wisdom, not discovering new knowledge or handling unprecedented events like the plague.
Practical experience was minimal. Unless students were lucky enough to attend a university where they could follow a professor on hospital rounds, hands-on training was scarce. Surgery was generally left to barber-surgeons trained through apprenticeships, not universities, so medical students didn’t learn surgical techniques.
Anatomy was usually taught from diagrams. Human dissection slowly emerged, possibly starting in Bologna in the mid-13th century (perhaps linked to forensic pathology for its law school). Montpellier followed about a century later. Getting bodies wasn’t easy. There were ethical concerns – nobody wanted to see their relative on the dissection table! Often, corpses had to be brought in from other towns.
A typical dissection involved a professor reading aloud from a text (often Galen’s descriptions of ape anatomy, as he wasn’t always allowed to dissect humans) while a surgeon or assistant actually did the cutting and displayed the organs. It was very much in line with the scholastic method: the text was the authority, even over what might be visibly different in the human body on the table.
Dissection was serious business. Rules stated you needed permission from the rector to get a body. To prevent chaos or maybe just keep things exclusive, no more than 20 people could watch a male dissection, and only 30 for a female one. Attendees had to be medical students in their third year or later. And if you saw one male dissection, you couldn’t attend another that same year. You could see a female dissection once, and that was it.
Astrology, learned during the earlier arts degree, became a massive part of medical training from the 13th century onwards. Each body part was thought to be governed by a zodiac sign, and understanding these connections helped diagnose illness or choose the right time for treatments. Bologna, for instance, required medical students in 1405 to study astrology all four years; they were students of “physica et astrologica.” Paris was a major center until the 1530s. Interestingly, later opposition often came from clergy or philosophers, not the physicians themselves. One scholar even claimed a doctor without astrology “is a blind man.”
After years of study, graduation involved a public oral exam, a Latin speech, and receiving symbols of the profession: a book, a ring, and a beret. Then came the celebratory banquet and handing out gifts (pouches of coins) to teachers and colleagues. At around 25 years old, the new doctor was ready to practice, often joining a guild and becoming one of society’s most respected professionals.
Trying to Understand the Black Death: Medieval Ideas
Armed with this ancient knowledge, how did medieval physicians explain the horrific plague that arrived in 1348? They relied on their established framework, often thinking in terms of a hierarchy of causes.
God, Sin, and Sickness
First and foremost, few doubted God’s role. Even with their “rational” Galenic medicine, physicians acknowledged divine power. The Bible was full of stories where God used disease as punishment. A catastrophe on the scale of the Black Death had to be a sign of God’s anger at humanity’s sinfulness. Archbishop William Zouche of York wrote in 1349 that the plague was caused by the “sins of people” forgetting God amidst prosperity. The King of Sweden agreed: “God for the sins of man has struck this great punishment.” Even physicians like Henry Lamm stated it was “better to say that the epidemic comes from God.” Chronicler Gabriele de’ Mussis blamed the “mire of manifold wickedness” humanity was wallowing in. Explaining the deaths of innocent children was harder, often falling back on ideas of original sin or punishment for the parents’ sins.
If God was the ultimate cause, many believed He used the heavens as His instrument. Natural philosophers like Albert the Great had taught that planetary conjunctions could cause pestilence. He claimed Mars and Jupiter aligning in a “warm and humid” sign would ignite earthly vapors, creating “pestiferous vapors.” In October 1348, the medical faculty of the prestigious University of Paris, asked by the king for an explanation, famously blamed a specific conjunction of Saturn, Jupiter, and Mars that occurred at 1:00 PM on March 20, 1345. This astrological explanation became widely accepted and repeated for centuries. Comets were also suspects, believed (following Aristotle) to corrupt the air as they passed.
The immediate cause, drawing from Hippocrates, Galen, and especially Avicenna, was corrupted air or miasma. Avicenna described how “vapors and fumes rise into the air, and provoke its putrefaction.” When this bad air reached the heart, it rotted the body’s “complexion” and caused a deadly fever. People had long associated foul smells (from swamps, corpses, waste, stagnant water) with disease. Medieval towns tried to legislate against stenches, believing “stink kills.” Some even thought earthquakes released trapped noxious vapors from the earth, corrupting the air – a theory that lasted surprisingly long.
Since everyone breathed the air, its corruption explained the plague’s widespread nature. But why didn’t everyone get sick? Physicians concluded some people were more susceptible. Based on humoral theory, those naturally “warm and moist” (like women and children) or overweight people, or those eating “warm and moist” foods, were considered most at risk. Certain activities also increased susceptibility: exercising, having sex, or taking hot baths opened the pores, supposedly drawing the corrupted air in faster. When seemingly healthy “cool and dry” people died, explanations ranged from hidden imbalances to simply God’s will.
Once the corrupted air entered through the lungs or skin pores, it generated a poison inside the body. This poison circulated, but the critical point was preventing it from reaching the heart. The body had natural ways to expel poison, physicians believed. Depending on its “weight,” the poison would move towards major organs suited for detoxification: the brain (expelling behind the ears), the heart (armpits), or the liver (groin). These, not coincidentally, were the exact spots where the plague’s characteristic swollen lumps, or buboes, usually appeared. Doctors saw buboes as a good sign – the body successfully pushing the poison out. If the buboes “ripened” and burst, recovery was possible. If they hardened or never appeared, the outlook was grim.
Things got complicated because observation suggested plague didn’t just come from bad air. People seemed to catch it directly from others. An anonymous physician in Montpellier described how the “air spirit emitted from the sick person’s eyes” could strike a healthy person nearby, transmitting the poison. Florentine chronicler Matteo Villani wrote that infection seemed caught “by the sight and by the touch.” Physician Gentile da Foligno noted in 1348 that “communication of the evil disease happens principally from contagious conversation.” Others observed people dying “in healthy air simply through contagion.”
This raised tricky questions. If it spread by touch, what was the role of air? Maybe the poison passed directly through skin pores? And what about catching it from objects – clothes, furniture, coins? People observed deaths linked to handling “infected” items. These inconsistencies between miasma theory and observed contagion were never fully resolved by medieval physicians, but the practical implication was clear: avoid bad air, sick people, and their belongings.
Medical Training Evolves (Slowly)
Fast forward a couple of centuries. Did medical education change much between the Black Death and the 1700s? Yes and no.
The number of medical schools and doctors certainly increased. Around 1500, Oxford and Cambridge produced maybe five doctors per decade; France had 2 medical schools, graduating about 2 physicians per year between 1390-1500. By the 1660s, 9 French schools were graduating nearly 70 per year, and France had 19 schools by 1700. However, quantity didn’t always mean quality; scholars suggest standards often dropped, except perhaps at Paris.
Frustratingly, even during the Renaissance and the Scientific Revolution, the core medical curriculum remained stuck in the past. Humanist scholars produced better, cleaner editions of Galen, Hippocrates, and Aristotle in the original Greek, and the printing press made these (and some newer texts) more available. But these ancient works remained the primary teaching tools, not just historical artifacts. Students now often learned Greek, but the fundamental reliance on ancient authority persisted.
There were some updates. Prompted by Renaissance curiosity, schools added courses on pharmacy and medicinal botany. The discovery of the Americas, with its thousands of new plant species, forced botanists to move beyond ancient Greek texts that described only a few hundred.
Anatomy theaters for public dissections became much more common and even popular spectacles, as shown in Rembrandt’s famous painting “The Anatomy Lesson of Dr. Tulp” (1632). Felix Platter, a student in the 1550s, described attending dissections at Montpellier with nobles, townspeople, and even monks and young girls watching. Getting fresh corpses sometimes involved shady methods:
Felix Platter’s journal reveals a world familiar with death. He describes accidentally bumping into a hanged corpse in the fog and riding past execution sites decorated with human remains. He even witnessed brutal executions. Plague itself was no stranger. To practice anatomy beyond official demonstrations, Platter and his friends became grave robbers. He recounts sneaking into a cemetery at night with accomplices, “swords in hand,” digging up a freshly buried woman’s body with their bare hands, wrapping it in cloaks, and carrying it off for secret dissection. They later stole the bodies of a child and a fellow student. Eventually, armed guards were posted at the cemetery gates.
Sometimes, the professor himself might perform the dissection, as depicted in a 1581 painting of John Banister lecturing in London, indicating a slight shift towards more hands-on involvement by the physician. Surgery also began entering the curriculum at some schools in the 16th century, despite opposition from physicians’ guilds who saw it as a lower craft. It was as a surgery professor at Padua that Andreas Vesalius produced his groundbreaking, highly accurate anatomical atlas, On the Structure of the Human Body (1543), based on actual human dissection.
Perhaps the most important advance was the introduction of systematic clinical teaching – learning at the patient’s bedside. Giambattista da Monte started this at Padua’s hospital in the 1540s, and his students spread the practice. Experience slowly started to gain ground as a source of authority. Daniel Sennert, a famous early 17th-century professor, believed “experience is the teacher of all things” and should trump even ancient authors and reason.
However, change was glacial. Vesalius himself experienced the resistance. When he gave a dissection lecture at Bologna in 1544 demonstrating findings that contradicted Galen, the audience erupted into a furious debate about the relative merits of Galen and Aristotle, completely ignoring Vesalius’s actual observations. He reportedly left in disgust.
The most radical challenge to Galenic medicine came from Paracelsus (c. 1493-1541). He rejected humoral theory, seeing illness as specific problems in specific organs. He advocated using chemical remedies (iatrochemistry) based on three principles – sulfur, mercury, and salt – linking inorganic chemistry to organic health. His ideas were tied to alchemy and mysticism, and he saw his medical reforms as part of the Protestant Reformation’s divine plan. While influential in biochemistry’s history, Paracelsus and his followers were often dismissed as “magicians,” and their ideas didn’t significantly change how plague was understood or fought during this period.
Bostocke passionately argued that Galen’s “heathenish physic,” based on Aristotle’s “heathenish philosophy,” was flawed because it didn’t acknowledge God’s creation properly. He claimed Galenic doctors didn’t understand man as a “Microcosmus” (little world), misdiagnosed diseases, used inappropriate medicines, and wrongly attributed causes to heat and cold instead of understanding the “mechanical spirits and tinctures of impure seeds” (referencing Paracelsian chemical/spiritual ideas) that truly caused illness.
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Explaining Plague in a Changing World
So, with new discoveries happening in anatomy and chemistry, and the world changing through Renaissance, Reformation, and early science, did theories about the plague itself change dramatically? Mostly, no. Old ideas proved remarkably sticky.
Attributing plague to God’s wrath remained common throughout the 16th and 17th centuries. Even Paracelsus acknowledged God as the ultimate giver and taker of disease. Protestant reformers like Thomas Brasbridge, while rejecting astrology, blamed sin and urged repentance. Dutch professor Isbrandus van Diemerbroeck described pestilence as a God-created venom. Writing about London’s 1665 Great Plague, physician Nathaniel Hodges saw clear “footsteps of an over-ruling power.” The Reformation added a new twist: Catholics might blame Protestant heresy for God’s anger, and Protestants might blame Catholic “blasphemy.”
Luther offered a slightly different theological take. He believed the devil was the author of grave illnesses, using natural means to corrupt the body’s humors. God also used natural means (food, sleep) for health. Therefore, the physician was “our Lord God’s mender of the body,” repairing the damage done by Satan, just as theologians healed the spirit.
Astrological explanations also endured. Numerous Spanish physicians cited celestial causes in the 17th century. French doctors blamed “evil constellations” and eclipses for plague outbreaks in the 1620s and were still considering the moon a factor as late as 1785. A Milanese doctor in 1631 linked Saturn ruling the ears to buboes appearing behind the neck. The Austrian court physician in 1679 blamed a Mars-Saturn conjunction. It seems astrological theories may have held on longer in Catholic regions potentially tied to scholastic traditions.
While miasma (bad air) remained a popular theory, some thinkers tried to explain contagion more specifically. Girolamo Fracastoro in 1546 proposed that plague wasn’t just rot, but involved tiny “seedlets” (seminaria) that floated in the air, entered the body, and multiplied, causing disease. These seeds originated in the stars but could also be generated and passed along by infected people. Scientist Robert Boyle later theorized about tiny “poisoned corpuscles” in the air.
Using an early microscope, the Jesuit scholar Athanasius Kirchner examined the blood of plague victims in the 1650s and reported finding tiny “worms,” which he blamed for the disease – an observation remarkably close to discovering bacteria, though the real breakthrough was still centuries away.
Many theories still revolved around humoralism but increasingly focused on the conditions of urban life, especially among the poor. Dr. Donzellini of Verona (1577) listed causes like malnutrition, overcrowding, pollution, and eating spoiled food scavenged from markets. The London College of Physicians cited familiar culprits like slaughterhouses and bad drainage, but added newer concerns like increased urban building and overcrowding. Pamphlets listed bizarre specific triggers, like drinking beer in a hot room or eating cucumbers, eel pie, or gooseberry custard.
Conclusion
Throughout the long centuries of the Second Pandemic, from the Black Death’s arrival in 1348 to the early 18th century, physicians fought valiantly but were hampered by their own understanding of disease. Their medical education, deeply rooted in the ancient theories of humors proposed by Hippocrates, Aristotle, and Galen, changed remarkably little despite the monumental shifts happening in society during the Renaissance, Reformation, and Scientific Revolution. While new observations about anatomy and contagion emerged, and alternative theories like Paracelsus’s briefly flickered, the old framework largely held sway. Explanations for plague continued to blend divine wrath, astrological events, miasma, and confused notions of contagion. The real revolution in understanding plague – identifying the bacterium Yersinia pestis – wouldn’t happen until the late 19th century. Until then, doctors did the best they could with the knowledge they had, a knowledge that proved tragically inadequate against one of history’s deadliest killers.
