In 1348, nobody understood what actually caused the Black Death, so nearly every prevention method people tried was based on wrong assumptions. The plague killed roughly a third of Europe’s population, and the strategies available ranged from burning aromatic herbs to fleeing entire cities to wearing gemstone amulets. Some of these measures were useless. A few, almost by accident, offered a sliver of real protection. Here’s what people in 1348 believed, what they tried, and why most of it failed.
What People Thought Caused the Plague
The most authoritative explanation came from the medical faculty at the University of Paris, which issued an official report in October 1348. Their verdict: the plague was caused by a cosmic event. Specifically, a conjunction of three planets in the constellation Aquarius on March 20, 1345. Jupiter, being “wet and hot,” supposedly drew evil vapors from the earth, while Mars, “immoderately hot and dry,” ignited those vapors. The result, they claimed, was corrupted air filled with noxious fumes, lightning, and sparks.
This theory drew on Aristotle and other ancient authorities who linked planetary alignments with mass death. It also dovetailed with the dominant medical framework of the era: miasma theory. People believed disease spread through “bad air,” foul-smelling vapors that entered the body and disrupted its internal balance of fluids (the four humors: blood, phlegm, yellow bile, and black bile). If you could avoid or neutralize the poisoned air, the thinking went, you could avoid the plague. Nearly every prevention strategy in 1348 flowed from this single, incorrect idea.
Purifying the Air With Scent
Since bad smells meant bad air meant disease, the most common prevention tactic was surrounding yourself with pleasant or pungent scents. Wealthy households scattered cloves, cinnamon, and fennel across their windowsills, hoping to cleanse incoming air before it reached them. People burned sweet-smelling herbs indoors using fumigation torches. Oranges studded with cloves, a tradition we now associate with Christmas decorations, originated as plague preventatives hung around the home.
When venturing outside, people carried vinegar-soaked sponges to hold against their noses while walking through city streets. Vinegar was considered the cornerstone of the anti-miasma toolkit. Some carried it in ornate containers. One surviving artifact is a small silver skull that once held a vinegar-soaked sponge for exactly this purpose. The logic was straightforward: if plague traveled through foul air, then breathing through a filter of strong scent would block it. It didn’t work, because plague doesn’t travel through smells, but the practice persisted for centuries.
Sitting Between Two Fires
Pope Clement VI, based in Avignon during the outbreak, took a more dramatic approach. He sat between two enormous fires kept burning continuously in his chambers. The idea was that the heat would purify the surrounding air. As it turns out, this may have been one of the few prevention methods that offered any accidental benefit. The bacterium that causes plague, Yersinia pestis, is destroyed by high heat, and the fires likely kept fleas (the actual carriers of the disease) away from the Pope’s immediate vicinity. Clement VI survived the Black Death.
Bonfires and fumigation fires were also lit in public spaces across Europe, filling streets with smoke in hopes of burning away the invisible poison. Towns sometimes mandated that fires be kept burning at crossroads and in marketplaces. The fires did nothing to stop the bacterium directly in open air, but in enclosed spaces, they may have repelled the fleas that were silently spreading the disease from rats to humans.
The Rule of Flight
The single most effective piece of advice circulating in 1348 was summed up in three Latin words: “Cito, Longe, Tarde.” Leave fast, go far, come back late. This was the prescription favored by those with the means to follow it. Wealthy families, nobles, and clergy abandoned plague-stricken cities for rural estates, sometimes disappearing for months.
Flight genuinely worked, for the simple reason that it removed people from areas dense with infected rats and fleas. But it created its own problems. Those who fled had to figure out where it was safe to go, how to protect their property while absent, and which travelers or trade goods might carry the plague with them. For the vast majority of the population, farmers, laborers, the urban poor, flight was not an option. They stayed and died in enormous numbers.
Quarantine and Isolation
The Black Death prompted some of the earliest formal quarantine systems in European history. In 1348, the Republic of Venice established a council with the power to detain individuals and entire ships in the Venetian lagoon for 40 days before allowing them entry. The Italian word “quarantina,” derived from “quaranta” (forty), gives us the modern word quarantine.
Decades later, in 1377, the city of Ragusa (now Dubrovnik, Croatia) enacted a formal decree requiring ships arriving from infected or suspected areas to remain isolated for 30 days, a period called the “trentina.” Land travelers faced a 40-day isolation. These measures were imperfect and came too late for many cities during the initial 1348 outbreak, but they represent a genuine public health innovation that would be refined over the following centuries. Avoiding contact with sick people and crowded places was, in fact, sound advice. Nearly half of the plague treatises written during this period acknowledged that the disease appeared to be contagious, even if no one could explain why.
Diet, Bathing, and Daily Habits
Medieval physicians organized their prevention advice around what they called the “six non-naturals,” the controllable aspects of daily life believed to influence health. These included air quality, food and drink, sleep, exercise, emotional state, and what the body retained or expelled. Plague treatises almost always included detailed dietary recommendations. People were advised to avoid foods considered “hot and moist” in the humoral system, since the plague itself was thought to arise from hot, moist planetary conditions. Rich meats, certain fruits, and excess wine were discouraged. Light broths, vinegar-based preparations, and dry foods were preferred.
Bathing was widely discouraged during plague outbreaks. The belief was that warm water opened the pores, allowing corrupted air easier access to the body’s interior. This advice, followed seriously across much of Europe, likely made things worse by reducing basic hygiene. People were also warned to manage their bedchambers carefully, keeping windows shut against outside air and fumigating rooms with burning herbs before sleep.
Amulets, Gemstones, and Magical Protection
For those who could afford them, gemstones and amulets offered another layer of supposed defense. Medieval medical and magical traditions held that certain stones had the power to draw corruption from the body. Sapphire rings were prized. The toadstone, actually a fossilized fish tooth, was considered especially potent. Despite its name (people believed it came from the head of a toad), it was described in ancient medical texts as a panacea capable of pulling venom and disease from the body, and it found specific application as a plague remedy. These materials were set into rings and worn directly against the skin, where their healing properties were thought to work continuously.
The tradition connecting gemstones to plague prevention was rooted in astrology and the belief that earthly materials resonated with celestial forces. Since the plague itself was blamed on planetary alignments, it followed logically (within that framework) that stones governed by favorable planets could counteract the disease. There is, of course, no mechanism by which any gemstone affects bacterial infection.
Religious Responses and the Flagellants
Many people in 1348 viewed the plague as divine punishment, which meant the only true prevention was spiritual. Prayer, fasting, and religious processions swept across Europe. The most dramatic expression of this belief was the flagellant movement. Groups of pilgrims traveled from town to town, walking two by two in tunics marked with red crosses. Upon arriving in a public square, they would strip down and scourge themselves with whips until blood ran down their backs, performing penance they believed would appease God’s anger and halt the pestilence.
Witnesses reported feeling deep sadness at the sight but also hope that such sacrifice might save them all. Miracles were claimed in many places where the flagellants performed. Church authorities eventually condemned the movement, partly because it operated outside clerical control and partly because the large gatherings of flagellants almost certainly helped spread the disease further.
Why None of It Worked
The Black Death was caused by the bacterium Yersinia pestis, transmitted primarily through the bites of infected fleas living on rats. When a flea feeds on a plague-infected rodent, the bacteria multiply in its gut, eventually blocking its digestive system. A “blocked” flea, unable to feed properly, bites repeatedly and regurgitates bacteria into each new host. The disease can also pass between flea generations through their eggs, allowing plague to persist quietly in flea populations for long periods between outbreaks.
None of this was understood in 1348. The actual cause of transmission, flea bites, was invisible to people focused on planetary alignments and poisoned air. Vinegar sponges did nothing against fleas. Gemstones did nothing against bacteria. Prayer did nothing against rats nesting in thatched roofs and grain stores. The few measures that helped, fleeing infected areas, isolating incoming travelers, and (accidentally) repelling fleas with fire and heat, worked not because of the theories behind them but despite those theories. The beaked plague doctor mask, often associated with the Black Death in popular imagination, wasn’t even invented until the 17th century, credited to the French physician Charles de Lorme. In 1348, physicians had no special protective equipment at all.
If someone in 1348 had wanted to genuinely reduce their risk, the most effective strategy would have been to leave the city immediately, avoid all contact with travelers and the sick, live in a clean rural setting away from rats, and stay there for months. That advice, “Cito, Longe, Tarde,” was available. It just wasn’t available to most people.