Making Sense of the Black Death

Lydia Searle, Dickson College, 2012

The following essay was written as part of the High Middle Ages unit at Dickson College, Semester 2, 2012. It was written in response to the following question: 'What did medieval Europeans believe was the cause of the Black Death?'.

The Black Death was arguably medieval Europe’s worst pandemic. The plague spanned three years, between 1348 and 1350 AD, and devastated the population of Europe. Scholars suggest that 25 million people died over the course of the Black Death- roughly one third of Europe’s people (Byrne 2004). Modern research has shown that the cause of the plague is the bacteria known as Yersinias pestis (Y. pestis), carried to Europe by the fleas borne on the backs of rats travelling along the Silk Road. Scientists have also been able to classify the plague into three strains according to which bodily system is affected; bubonic plague, which attacks the lymphatic system; pneumonic plague, which attacks the respiratory system; and septicemic plague, which attacks the circulatory system. However, this was certainly not known whilst the Plague was raging through Europe - in fact there was no contemporary source that correctly described the cause of the plague (Gottfried 1983). The causes of the plague considered by contemporary authors and the people of Europe were much simpler and less advanced. They believed that plague was caused by te wrath and will of God, environmental factors and even the Jewish people.

God as the cause of the plague was perhaps the explanation that seemed most obvious to medieval Europeans. In those times, religion and God pervaded every facet of life, and God was the supreme controller of everything ( 2012). The importance of religion was paramount, taught to everyone of every class, and so it was an explanation that could be understood and accepted by all. Byrne (2004) states that medieval European scholars followed Aristotle’s assertion that there were four causes for everything: a maker, a plan, material and a reason. They believed that God was the plague’s maker, and his reason was the sin of mankind. Biblically, plague is portrayed as a means of divine punishment, as is shown in the Ten Plagues brought against Egypt. Similarly, Byrne concludes that medieval Europeans thought that this scourge was a punishment brought against them for their sins. He writes that people had become less pious, taking their blessings for granted so that when they were hit by the Black Death they thought that the plague was “surely caused by the sins of men who, while enjoying the good times, forget that such things are the gifts of the most high giver” (Byrne 2004, p 39). This position is supported by Kelly (2006) who writes that King Magnus II of Sweden declared to his subjects: “God, for the sins of men, has struck the world with this great punishment” (p275). The majority of people believed this theory, with physicians and even the professors at the Medical Faculty of the University of Paris accepting or at least acknowledging the divine causation. There were however some people who did, if not deny the hand of God in the plague, disagree with the extent of his involvement. Although nearly everyone accepted God’s role there were also other, more worldly, theories in circulation.

Environmental factors were considered by many scholars to be the cause of the Black Death. There were three main factors that were thought to have contributed: miasmas, or corrupted air; earthquakes; and planetary alignments. The proponents of these theories were not really rejecting the idea that God had a hand in the plague - Byrne (2004) states that in the Compendium de Epidemia per Collegium Facilitatus Medicorum Parisius the professors at the University of Paris acknowledge God’s role. Rather, they were exploring a more scientific cause for the plague. The suspicion of environmental causes was not unprompted; in the year preceding the plague there was significant environmental upheaval. Kelly (2006) writes that in April of 1348 earthquakes hit Rome, Venice, Pisa, Bologna and Naples, as well as various regions in Germany. A chronicle from the monastery of Neuberg in Austria reports a deadly rain mixed with serpents and fires with contagious smoke in the year before the plague hit (Horrox 1994). The seasons were unusually warm and hot, which medieval people interpreted to be an imbalance of the humours tending towards the malignant hot and moist humours, which caused sickness (Kelly 2006). The effect of these environmental factors on health was not a new idea- Hippocrates had cited air corrupted by earthquakes as a cause for sickness in his works (Byrne 2004). The theory went that earthquakes ruptured the earth’s surface, releasing poisonous gases that corrupted the air, leading to miasmas. The corrupt air was thought to be blown on a southern wind and, once breathed in, “penetrates to the heart and corrupts the substance of the soul there” (Kelly 2006, p 18). Planetary alignments were also considered to be a cause of these miasmas and therefore a cause of the plague. The Compendium states that: "The first cause of this pestilence was and is the configuration of the heavens in 1345, at one hour after noon on 20 March, when there was a major conjunction of three planets in Aquarius." (Kelly 2006, p 169). The planets were each associated with certain humours, and the planets in conjunction were associated with the bad warm and moist humours, making their conjunction even worse in terms of effect on health. This theory was well received by scholars because it had a basis in accepted scientific fact rather than theology. Still, there were those who chose to place the blame again closer to their world and the people in it.

Related Article: The Plight of the Jews in a Time of Plague
Another contemporary explanation for the plague lay with the Jewish people. Bowsky (1971) writes:

When ignorant men are overwhelmed by forces totally beyond their control and understanding it is inevitable that they will search for some explanation within their grasp. When they are frightened or badly hurt then they will seek someone on whom they can be revenged (p 73).

The people were looking for a scapegoat, and they found it in the Jews. As a minority which was already disliked and unpopular, the Jews made the perfect candidate. There was really only one charge levelled directly at the Jews- the accusation that they were poisoning wells and thereby infecting people with the plague. The accusations began as rumours, but in the summer of 1348 several Jews were captured in Chillon, Switzerland and tortured until, naturally, they confessed (Kelly, 2006). These confessions gave credence to the rumours and sparked a formidable wave of anti-Semitism throughout Europe. Over the summer the rumours evolved until they were a full-blown conspiracy theory. There were elaborate descriptions of the poisons used and discussions of the hierarchy involved- Kelly (2006) asserts that a rabbi known as Father Jacob was thought to be the mastermind of the plot, with an army of poisoners at his disposal. This theory may have been supported by the fact that fewer Jewish people seemed to be dying than Christians, but it is now known that this was most likely due to the superior hygiene practices of the Jewish people. Nonetheless, Jews did die, but this did little to alleviate the suspicion that the Jews were behind the plague. Instead, it served to bolster the opinion that the Jews were endlessly cunning and sneaky. There were some people who tried to help the situation of the Jews- Queen Jeanne of Southern France and King Pedro IV both tried to protect their Jewish subjects, but the fear caused by the plague combined with the ability for people to physically do something that they thought would help them meant that pogroms continued.

Another motivation for the pogroms and accusations against the Jews was their position as a money lending class. People thought that by wiping out the Jews they would also erase their debts (Ziegler 1969). People arguably also thought that their tolerance of the Jews- the alleged Christ killers- was one of the sins that had brought God’s wrath upon them, and that by destroying them they had some hope of placating him and ending the plague. Ultimately though, it was the poisoning of the wells that was the most profound and widespread belief to be how the Jews caused the plague.

Although no contemporary source correctly described the cause of the plague, there is evidence to suggest that the people were not totally ignorant. Scientists have now discovered that Y. pestis is a unique strain of bacteria in that it is not only spread by animals, but it can also be spread from human to human. This contagiousness undeniably affected the success of Y. pestis and therefore the vast spread of the plague. There were however some areas in Europe that were less affected than others. Venice and Milan both got off quite lightly, and this has been attributed to the actions that these cities took at the first signs of the plague. In Milan, people who were sick or had come into contact with the sick were kept away from the rest of the population in a process remarkably similar to today’s quarantine (Aberth 2011). This practice wasn’t observed elsewhere; in most cases families would stay and try to help the sick. Similarly to Milan, when the plague hit Venice in 1348, the Venetian Great Council formed a plan to reduce its impact. They closed off their ports and seaways, not allowing boats to enter until they were sure that the people on board were healthy (Jones 2011). Though these actions may seem cruel, they were effective in circumventing the brunt of the plague’s devastation. These actions also show that people were at least partially aware of the contagious nature of the disease, which would have been a quite sophisticated concept at the time. Aberth (2011) suggests that this was not the only progressive idea relating to plague in that time, stating that “a significant handful of Christian Europeans resisted the notion that God had anything to do with the disease” (p. 43). This idea would have been exceptional in that very few people would consider that god did not have a hand in such a colossal, impactful event. He writes that the main supporters of this theory were Konrad of Megenberg- a German Catholic scholar and, interestingly, priest- and Giovanni della Penna. The actions of Venice and Milan as well as the ideas of Konrad of Megenberg and Giovanni della Penna show that there were some accurate identifications of plague causes.

The ideas on what caused the Black Death in the Middle Ages were varied and would today be considered quite outlandish. There were some progressive thinkers who made correct assertions, but the majority of people blamed God, thinking that their sins had caused him to unleash the plague on them; they blamed earthquakes and the planets for causing deadly miasmas that corrupted the air they breathed; and, perhaps most incomprehensibly to people today, they blamed the Jews, alleging that they were contaminating all of Europe by putting poison in the village wells. These explanations are now known to be false, but they were widely accepted by medieval Europe’s people as they were the only explanations that made sense in a world bereft of the scientific knowledge of today.


Subject Author Replies Views Last Message
No Comments


Aberth, John (2011), Plagues in World History, Rowman and Littlefield, Maryland
As I viewed this text online I was missing certain parts, but what I read was well written and informative, with lots of contemporary backing for what was being said.

Bowsky, William (1971), The Black Death - A Turning Point in History?, Robert E Krieger Publishing Company, New York
This book contains a variety of contemporary views from many authors, with particularly useful material on the pogroms. Being published in 1971, the scientific information seems a bit out of date (Y. pestis is still referred to as Pasteurella pestis), but the rest of the information seems reliable and unbiased.

Byrne, Joseph (2004), The Black Death, Greenwood Press, USA
This book also had lots of relevant information, particularly concerning the environmental causes of the plague. It was unbiased and presented different sides of the argument where they existed.

Jones, Kaye (2011), 'The Black Death: Exposing Myths and Lesser Known Facts'. Retrieved November 20, 2012, from
This website was easy to read and informative, with information specific to what I was looking for, so that was useful.

Kelly, John (2006), The Great Mortality - An Intimate History of the Black Death, Harper Perennial, London
This source was very useful as it contained in depth coverage of a variety of relevant topics. The information was backed up by contemporary quotes.

Gottfried, Robert (1983), The Black Death, The Free Press, USA
This book did not have much information relevant to this essay, but did have some information on environmental causes. It was seemingly unbiased but not very useful.

Horrox, Rosemary (1994), The Black Death, Manchester University Press, Manchester
This book contained a variety of translations of contemporary sources so was very useful to get a true idea of what people thought in medieval times.

Ziegler, Philip (1969), The Black Death, Collins Clear Type Press, London
This book did not have a lot of information about the causes of the plague, and what was there was written in a way that I found a bit difficult to understand, but it seemed reliable.