"Nor, for all their number, were their obsequies honored by either tears or lights or crowds of mourners rather, it was come to this, that a dead man was then of no more accot than a dead goat would be to-day." [01]
The Black Plague hit Western Europe in 1347 and would recur every generation for nearly 300 years, though the mid-fourteen century outbreak is generally regarded as the worst case. The plague devastated Europe, eradicating between 25 to 33% of Europe's population. Unsurprisingly, the plague was an innately urban phenomenon. While small towns and villages did suffer, they didn't have the high population density and lack of sanitation in big cities. A survey by the papacy indicated there were 42,836,486 deaths around the world (compare this to nearly 55 million total deaths occurred during World War II). In addition, nearly 200,000 towns were depopulated across Europe. [02]
The plague would effect European society in nearly every aspect, from religion to politics. With the pre-existing gloom the continent was already plunged in, the Black Death served to bring about the Dark Ages for Europe. When the shadow of the plague was finally lifted, Europe would emerge ready to form foundations for the modern world.
While it is usually glossed over in most histories students read, a very nasty strain of bacteria - yersinia pestis - stormed through Asia in the mid-1340s. This bacteria would hit the Black Sea in 1347. A year later, it would reach Italy, thanks to trade ships carrying the infection, and spread as far north as Venice and as far west as Avignon. By the middle of the year, Paris had reported cases of the Black Death. Nearly 80% of France fell in the plague's grasp, and a significant portion of Eastern Spain was infected as well. At the end of the year, the plague had crossed the Po River. Trade ships had once again taken it across a major body of water - in December, 1348, London began to have its first cases of the plague. By the end of 1349, the plague could be found in nearly all of England and several northern nations. The outbreak reached its height at the beginning of 1351, when it could be found as far north as the Baltic Sea, near modern-day Poland, Latvia, and Estonia. [03]

Propogation of the Black Plague in Europe
[04]
Symptoms
In the Decameron, Giovanni Boccaccio described the Plague's symptoms as:
"... in men a women alike it first betrayed itself by the emergence of certain tumors in the groin or the armpits, some of which grew as large as a common apple, others as an egg, some more, some less, which the common folk called gavoccioli. From the two said parts of the body this deadly gavocciolo soon began to propagate and spread itself in all directions indifferently; after which the form of the malady began to change, black spots or livid making their appearance in many cases on the arm or the thigh or elsewhere, now few and large, then minute and numerous." [05]
These "tumors", known as buboes, are the classic portrayal of the Black Death. There were, in fact, three varieties of the plague - the bubonic plague was the most common of them, spread by fleas and rats. The pneumatic plague was contracted through breathing. Although this was far rarer, it was also more hazardous because of how it was spread. A third version, the septicemic, targetted the blood system of the victim. [06]
Because
the latter two varieties of the plague were very rare, little is known about
them. Because of historical accounts, a significant amount of knowledge is
available about the bubonic plague. For example, Johannes Nohl in his Black
Death describes "burn blisters", which were the same black spots
that Boccaccio describes. These boils, which began about an inch in diameter
at most, grew to four or five times that size as the disease progressed. As
the boils grew bigger, the victims battled with increasing discomfort, often
vomiting blood which rose from the lungs to the throat. This, in turn, resulted
in the victim's body withering away to his or her eventual death. [07]
"The sickness lasted three days, and on the fourth, at the latest, the patient succumbed." [08]
Other accounts placed death, at most, one week to ten days after contraction of the disease. Anyone who was infected died within this time period - there were no cures for the Black Plague. Physicians of the time pronounced the sickness uncurable. [09] Death was painful; those who didn't contract the plague were subject to the deaths of those that did.
Yersinia Pestis and the Medical Profession
The
scientific name for the bacterium that caused the Black Death is Yersinia
pestis. A gram-negative rod prokaryote, Y. pestis passes on from
rats to fleas to humans.
Those involved in the medical profession during medieval times, of course, did not know the first thing about bacteria. As such, they were utterly helpless against such a malady. Even modern practitioners would be lost without antibiotics and modern medical advances. Without the benefit of such knowledge, most physicians sided with the Church, agreeing that the plague was a manifestation of the wrath of God. Though there were a few men who proposed some far out hypotheses (blaming it on comets, Jews, and the like [12]), their ideas are left for another section.
Bacteria thrive in certain kinds of condition (the exact variables depending on the type of bacteria). Y. pestis thrived under hot, summer conditions. This is readily apparent from a list of the number of burials in graveyards. Since gravediggers were paid to keep meticulous records, such lists are easily available in Grascia Morti (Books of the Dead). For example, graphing the number of burials during the plague years of the the 1300s, we can obtain:

Burials during Epidemic Years
[13]
Cures
Nearly every credible source on the Black Death points out the futility of most cures attempted by physicians and doctors of the time.
"On the whole the physicians were quite helpless in the face of the plague. The most eminent of them confessed it frankly. Chalin de Vinario declared: 'Every pronounced case of the plague is incurable.' " [14]
As
mentioned before, there were no cures for the Black Plague. There were
ways to avoid the Black Death - there were ways to get around it, to try and
run from it, and there were - of course - the almost-humorous "treatments"
some men prescribed, but there were no cures.
"As in most cases the disease terminated with death and all medical aid was of no avail, the protection of the healthy appeared of greater importance than the treatment of the sick." [15]
The best way to avoid the plague was to not be exposed to it. While the bubonic variety is not very contagious (rats and fleas spread it; human-to-human contamination is very rare), it was the most logical thing to run away from the plague to avoid it. Unfortunately, the vast majority of men and women could not afford to do that. As a result, only the wealthy and affluent - those with access to transportation and the means to afford and maintain it - could get away in time. Even this wasn't very useful - the plague spread through nearly all of Europe within a decade. There was no place to run and hide.
Another, easier, precaution doctors prescribed was to avoid exposure to plague victims. While this flew in the face of nearly every medieval sense of "morality", if the doctor himself avoided the patient, why wouldn't the everyday man and woman? Repurcussions of such behavior is examined in other sections of this website.
Unfortunately, none of these measures would prove to be of aid in the path of destruction that the plague laid out.
"There was no one who wept for any death, for all awaited death. And so many died that all believed that it was the end of the world." [17]