The Black Death: End of a Paradigm

SAMUEL K. COHN, JR.

HIV/AIDS and the threat of biological warfare have refueled interest in the Black Death among professional historians, biologists, and the public, not only for assessing the toxic effects of the bacillus but for understanding the psychological and longer-term cultural consequences of mass death. This article makes two arguments. Against the assumptions of historians and scientists for over a century and what continues to be inscribed in medical and history texts alike, the Black Death was not the same disease as that rat-based bubonic plague whose agent (Yersinia pestis) was first cultured at Hong Kong in 1894. The two diseases were radically different in their signs, symptoms, and epidemiologies. The proof of these differences forms the major thrust of this article. The second argument stems from the epidemiological differences between the two diseases. Humans have no natural immunity to modern bubonic plague, whereas populations of Western Europe adapted rapidly to the pathogen of the Black Death for at least the first hundred years. The success of their immune systems conditioned a cultural response that departs from the common wisdom about "plagues and peoples." As far back as Thucydides, historians have seen the aftershocks of pestilence as raising the levels of violence, tearing asunder secular cultures, and spawning pessimism and transcendental religiosities.1 A fresh reading of the late medieval sources across intellectual strata from merchant chronicles to the plague tracts of university-trained doctors shows another trajectory, an about-face in the reactions to the plague after its initial onslaught. This change in spirit casts new light on the Renaissance, helping to explain why a new emphasis on "fame and glory" should have arisen in the wake of the West's most monumental mortality.	1
One of the many memorable phrases coined in Johan Huizinga's The Waning of the Middle Ages is the title of its first chapter—"The Violent Tenor of Life." While this attempt to sum up the collective psychology of post-plague Burgundy and northern France hardly mentioned the plague,2 others following Huizinga's lead have argued that society became more violent precisely because of the plague, that the mass mortality cheapened life and thus increased warfare, crime, popular revolt, waves of flagellants, and persecutions against the Jews.3 But few have gone beyond recounting dramatic episodes taken almost exclusively from the first wave of plague to compare levels of violence before and after the Black Death, and few have hinted at differences in reactions between the Black Death of 1348 and its subsequent strikes in the fourteenth and the fifteenth centuries.4	2
In Florence, Genoa, Venice, and most of northern Italy, expenditures on warfare increased exponentially after the Black Death to the fifteenth century, as shown by the soaring of state indebtedness.5 In Siena, these fiscal pressures led in 1355 to the toppling of the most durable political regime in the history of the Italian city-states—the Nove—which had ruled since 1287.6 Afterward, popular unrest, factional conflict, and a rapid succession of governments filled the city's political chronicle. In one year alone, 1368, popular uprisings overthrew three regimes.	3
Yet the Italian post-plague political experience cannot be generalized. For England, the trend is nearly the opposite. Richard II's post-plague reign of peace (1386–1399) contrasts with the previous three Edwards' expenditures on war, their military operations in France and Scotland, and their new and horrific uses of violence, plunder, and torture to quell civilians and knights alike.7 Even within Tuscany, Siena's political history of stability followed by instability was not the norm. By contrast, factional strife riveted the political narrative of Florence during the first part of the fourteenth century to the extent that on two occasions its ruling elites forfeited their independence for stability by handing the government over to foreign rulers—Charles of Calabria in the 1320s and Walter of Brienne in 1342.8 After the plague, Florence's political history changed: the Albizzi reforms of 1393 heralded a new constitution and structure of political control that endured through most of the fifteenth century.9	4
Further, while political conflict may have increased among the new regional states of Italy from the Black Death to the Peace of Lodi (1454), internecine war between the great families in Florence declined; "the tenor of life" became less, not more, violent. Before the Black Death, magnate rituals of violence and tower warfare regularly brought Florence's ruling families into the streets, pitching one neighborhood against another, even after the victory of the popolani grassi and their laws of 1292 to curb magnate violence. The judicial sentences of the early 1340s show Florence's inability to end this violence or prevent its noble youth from riding out of town, pillaging the countryside, and killing peasants simply for the sport of it. But after the plague, the city government began effectively to curb these acts of violence, and by 1400 such raids disappear from the judicial ledgers.10 Conversely, in Genoa, it was after the Black Death that the number of "general, popular, and noble revolts" increased.11	5
While the medium and long-term consequences may continue to defy generalization, a sense of the immediate psychological consequences of the Black Death and its subsequent strikes can be scrutinized with greater clarity. The first sweep of plague, 1347 to 1351, provoked as close to a universal chorus as one hears in history. Merchant chroniclers, priests, and university-trained doctors claimed that this malady was new to world history, that doctors and medicine were useless, and that all that could be done was to pray for God's mercy. Explanations of the plague were not sought in the human sphere but in God's wrath and the configuration of planets. A chronicler of Viterbo called it "a divine plague from which no doctor could possibly liberate the stricken."12 Man's only contribution had been his sins. Not only those on the margins of Europe, such as the Olivetan friar of Prussia,13 but also humanists such as Petrarch's close friend Louis Sanctus of Beringen (called Socrates)14 and chroniclers such as the friar Bartolomeo of Ferrara, who claimed to have received his evidence from eyewitness merchant accounts,15 reported similar tales of the plague's origins—floods of snakes and toads, snows that melted mountains, black smoke, venomous fumes, deafening thunder, lightning bolts, hailstones, and eight-legged worms that killed with their stench.16 While the butchering and burning of the Jews and the flagellant movements of frenzied half-naked men and women were not universal throughout Europe, they swept across wide swathes of it from the east, Germany, Spain, southwest France, the Swiss cantons, and parts of the Low Countries.17	6
Historians have taken these first explanations and psychological manifestations of mass hysteria as the plague's enduring characteristics.18 Few have sought to compare the psychological reactions to plague over time, and when they do so (as René Baehrel did for epidemics in the seventeenth and eighteenth centuries), they find an "immobile history" of "constantes psychologiques."19 A reading of chronicles and doctors' plague tracts over the Black Death's first hundred years charts a different history: the initial explanations and attitudes did not persist. From chroniclers, merchants, and clerics alike, the floods of snakes and black snows that melted mountains vanish altogether from the "aetiologies" of subsequent strikes of the plague, and even though God and the stars as explanations continue with some, they rapidly decline even with monastic chroniclers of later plagues. Thomas Walsingham, a monk at St. Albans, retold a story of "a silly wretch" who during the fifth plague at Cambridge in 1389 danced grotesquely in front of the Host and was struck down immediately. Skeptical of hearsay evidence, Walsingham brushed aside "all sorts of explanations" and refrained from drawing moral lessons. Instead, his exemplum was clinical: the plague "attacked healthy men, who then died raving."20 The verse chronicler of the Premonstratensian abbey of Floreffe in Namur explained the plague of 1437 by pointing to the war in Liège, Namur, and Hainault. He reasoned that these political circumstances "gave rise to high prices, grain shortages, and famine," which ignited the plague.21 God was not mentioned.	7
While the Black Death may have initiated a new intensity in the history of Jewish persecutions, as David Nirenberg has recently argued for late medieval Spain,22 I know of only one instance of an outbreak of plague for the next hundred years that sparked a massacre of the Jews: in Poland in 1360, where, at least for Krakow and its surroundings, this appears to have been the region's first plague.23 By the mid-fifteenth century, rather than being targets, Jews participated alongside Christians in processions to forestall the plague.24	8
Similarly, subsequent plagues of the fourteenth and early fifteenth centuries failed to set off those wild and unsanctioned displays of emotion—the flagellant movements—that had frightened churchmen and secular authorities in 1349 and 1350. Instead, later movements such as the semi-nude flagellants at Liège, who attacked Simonists and fornicators in 1376, were local events and had no relation to plague,25 while other movements associated with plague were highly controlled, having been organized top down by town councils or the church.26 Some have supposed that the Bianchi movement of 1399–1400 in northern and central Italy was a revival of the 1348 religious hysteria,27 but insofar as it was associated with plague, it represented the opposite—a form of popular orthodoxy sanctioned by the church and praised for its orderliness. The Bianchi's mission was the preservation of public order.28	9
The change with the successive strikes of plague was not just one of a silence in the sources that replaces the earlier signs of desperation. From skepticism about remedies, cures, and preventive measures, doctors and chroniclers increasingly supplied solutions. One manifestation of the new confidence was the blossoming of what was effectively a new genre in late medieval writing, the plague tractatus, written mainly by doctors but also by clerics (and at least in one case by a schoolteacher).29 A census of this genre has yet to be taken, but while around fifteen are known in Western Europe for the first plague, over two hundred have been listed or edited from the 1360s to 1450, some with numerous manuscripts. The first tracts of 1348 explained the plague by planetary constellations. Later ones heeded what the famous doctor Gentile of Foligno may have suggested but failed to deliver in his own plague tracts of 1348: doctors ought to leave the stars behind and get down to the business of healing patients.30 By the second plague, the tracts rarely indulged in the long philosophical discussions of the plague's "remote causes"; instead, they began by prescribing specific cures and preventive measures—long lists of recipes, herbs and foods to eat or not eat, ointments to apply to plague swellings, instructions for lancing boils and for which veins to tap when letting blood.	10
One of the most famous of these tracts is that by the doctor of three popes, Guy de Chauliac, located within his Great Surgery, which remained a central medical text until the sixteenth century. Written in the immediate aftermath of the second plague at Avignon, it reflected first on 1348, concluding that nothing had been comparable in world history, that it was brought on by a certain configuration of Saturn and Jupiter, and that medical remedies were of no use.31 But with the second plague, his argument took a radical about-face. Instead of resignation, he offered specific procedures and prescriptions. They were, in fact, the ones Guy had used on himself while infected with "continuous fever and an ulcer in the groin" and that allowed him "to evade God's Judgment."32	11
By the second plague, other doctors reported similar medical success and wished to make their remedies known. At the end of the fourteenth century, another doctor, Stephanus of Padua, also turned to personal experience in his tract, describing his own and his wife's affliction with plague—four days "of horrendous fevers and the detestable signs," himself "at the head of the bed and she at the foot." With his regime of cures, he announced that they had "triumphed over plague." He now wrote down these tested cures to benefit his fellow citizens of Padua, to whom he dedicated his tract.33	12
With similar confidence, other doctors, such as John of Tornamira in the third plague at Montpellier, illustrated successful surgical procedures, by recounting clinical histories of his patients who survived the plague.34 A late fourteenth-century Venetian doctor claimed to have saved one hundred patients from plague with his recipes.35 The Portuguese physician of Cardinal Philip of Alenzolo boasted that none had died under his care in "a big plague" at the beginning of the fifteenth century.36 At about the same time, a doctor from Danzig said that a concoction he invented mixed with weak wine had cured many plague victims.37 At the end of the fifteenth century, a doctor from Cologne began his tract by saying that his "little work" had proven itself a success in treating plague patients in Rome and elsewhere throughout Italy. Others such as John of Burgundy in 1365 praised not only themselves but also their generation of new plague doctors. As a doctor from Cologne declared at the end of the fifteenth century, "through their industry and medical procedures [doctors] have liberated many plague victims from the illness."38	13
From these alleged successes, doctors such as Johannes Jacobi of Montpellier and John of Burgundy toward the end of the fourteenth century claimed to have surpassed the ancients in the art of healing.39 From the unknowable, even the unspeakable, plague was now seen as beneficial to medical progress: it had given post–Black Death doctors a new range of practical experience. Through the fifteenth century, doctors from Lübeck and elsewhere in Germany saw the plague in much the same terms, pointing to the experience and experimentation it provided.40 Far from being slavish followers of ancient or later Arabic authorities, as historians often assert,41 doctors of the late fourteenth and early fifteenth-century plagues were now often disdainful of these authorities, Hippocrates and Galen included. The new plague doctors relied on their own "experience" in place of the "auctores" in curing plague patients. Nor did these doctors represent a Renaissance intellectual elite from central or northern Italy; indeed, in at least one text, distance from the centers of the Renaissance was seen as an advantage. A fifteenth-century country doctor from a village within the diocese of Besançon asserted that in Bologna, where he had previously practiced, the doctors had no remedies for plague because they relied on Hippocrates and other ancients, who had no knowledge of the present plague. "Without wasting words" as he put it, he then described his own many remedies, by which he claimed to have cured patients of plague.42	14
With the fourth plague in 1382, the Avignon doctor Raymundus Chalin de Vivario was even less respectful of the ancients. Not only did they fail to understand the causes of plagues and "plainly could not cure" plague cases, they had "left everything in confusion."43 In 1406, the physician of the king of Aragon added other Greek and Arabic authorities to the list of hopeless ancients who had nothing of value to say about plague, and he ended by trumpeting his own credentials—forty years of plague diagnosis in Toulouse, Montpellier, and Sicily.44	15
By the early fifteenth century, the doctors were not alone in proclaiming their "triumph over plague." From utter despair, stargazing, and prayers to God, chroniclers began to proffer practical lessons and specific herbal remedies for facing plague. As the early fifteenth-century Florentine diarist Giovanni Morelli advised his heirs: those well armed against the plague stood a better chance of survival than the unprepared. He then defined being "well armed" as "observing diligently the remedies of valiant doctors."45 His view of doctors contrasts sharply with that of chroniclers of 1348 such as Matteo Villani or Agnolo di Tura del Grasso of Siena, who saw them as useless, desiring quick profits, and succeeding only in leading their patients more quickly to the grave. The sharp rise in doctors' salaries in Florence and probably elsewhere in Europe after the plague and into the fifteenth century shows that Morelli was not alone in praise and increased reliance on the medical profession.46	16
Chroniclers of later plagues turned to causes other than the stars, snakes, toads, or even God to understand the plague's origins and transmission. While Matteo Villani still considered sin at the root of the second wave of plague that spread through Germany and the north of Europe in 1357–1358, he also understood it in terms of human immunity, observing that it struck most vigorously those areas such as Brabant and Bohemia that had not been infected the first time around. Others, such as the Gatari chroniclers of Padua, pointed to war. In addition to corrupt vapors spreading from decaying corpses, war forced peasants and their animals into cities, causing overcrowding and unhygienic conditions that quickly erupted into plague and mass mortality. Their description of the preconditions of the plague in Padua of 1405, the war-inflicted overcrowding of peasants into the city with their animals, the ensuing mounds of mud, manure, and dead carcasses, sounds more like the analysis of an early epidemiologist's description of an infectious crowd disease such as typhus than a medieval chronicler explaining the moral and cosmic conditions that presaged plague. How do we explain the change in mentality? Could it have hinged on the character of the disease?	17
Throughout the twentieth century, historians and scientists alike have assumed that the "third" pandemic that struck Hong Kong in 1894 and spread across the oceans was the same disease that halved Europe's population in the mid-fourteenth century. Their assumption has rested on the supposed similarity of signs and symptoms between the late medieval and modern pandemics. According to Ann Carmichael, who combines an expertise in medieval history with one in medicine, "Boccaccio leaves no doubt that bubonic Y. pestis ravaged Florence in 1348. If the bubo predominated as a sign, we could still be reasonably comfortable after five centuries that there was not much error in the ascription of a death to plague."47 Nobel laureate and immunologist Sir Macfarlane Burnet has emphasized that diagnosis of diseases in the past must be assessed by epidemiology and not by signs or symptoms alone. But when he came to the Black Death, he forgot his lesson: "The symptoms are characteristic enough to make it easy to recognize the disease from classical or medieval descriptions, and we can be sure that the two greatest European pestilences, the plague of Justinian's reign (A.D. 542) and the Black Death of 1348, were both the result of the spread of the plague bacillus."48 As health workers in the subtropics are taught, the bubo or swelling in the lymph glands is not unique to bubonic plague. As early as the 1920s, editions of Manson's Tropical Diseases insisted that the presence of the bubo was not a sure sign that the malady was bubonic plague and advised doctors to take cultures of the infected area before treating for plague. The sign could equally well signify numerous other diseases: relapsing fever, severe cases of malaria, typhoid, typhus, glandular fever, tularaemia, lymphogranuloma inguinale, and various forms of filariasis.49	18
For some time, scholars have been puzzled by the inconsistencies between what contemporary doctors and chroniclers reported in the fourteenth and fifteenth centuries and what scientists observed on the microscopic and macro-sociological levels in mostly subtropical zones after the discovery of the plague bacillus. One might even argue that the cultural sophistication of doctors at the turn of the century—their knowledge of the late medieval past50 —was a factor that delayed for a decade or more their acceptance of the complex rat-flea-human vector in the transmission of modern plague. Such a slow and inefficient transmission did not square with the medieval plague, which from contemporary descriptions and the speed it traveled must have been an airborne disease, communicable person to person, and possibly transmitted as well by infested clothing and other objects, as chroniclers reported and governments tried to curb with new plague legislation.51 Without the assistance of the railway or the steamship, the fourteenth-century disease spread almost as fast per day over land as modern plague does per annum.52	19
Even after repeated observations and experiences of the plague ward as "the safest place" to be in times of plague,53 early twentieth-century doctors were reluctant to distinguish this disease from the rapidly infectious plague of the Middle Ages or to push aside the lessons they thought they had learned from the past. In India, even though relatives and friends crowded around plague victims, using their hands and clothing to wipe away discharges from the patients' mouths, and practicing "the common custom of receiving the sputa of the sick in their hands,"54 plague wards remained almost completely free of further infection. Yet until around 1907, doctors continued to treat the disease as though it were highly contagious.55	20
Nor does the pneumonic form of plague help solve the riddle, as modern historians continue to assume. First, with modern plague, cases of person-to-person transmission—pneumonic plague or secondary pneumonic complications after the onset of the buboes—have been rare. Secondly, unlike measles or influenza, "droplet" transmission of Yersinia pestis in its pulmonary form is extremely ineffective.56 The worst manifestations of modern pneumonic plague—Northern Manchuria in 1911 and 1921—were limited, the proportions killed under 0.3 percent.57 With both epidemics, the disease broke out among tarabagan fur hunters crammed in underground inns, 12 by 15 feet, where as many as forty men slept without adequate ventilation to protect themselves against the Siberian cold. Further, in packed railway cars between Harbin and Changchun, the spread and infectivity of this disease remained low. Comparing the Manchurian pneumonic plague and the late medieval pestilence that swept through Europe and Asia, the foremost authority on pneumonic plague, Wu Lien Teh, had doubts about the connection and speculated that the Black Death might have been "a virulent type of influenza such as that encountered in 1918."58 Such a speculation finds some support in the diagnosis of plague in Kashmir in 1903–1904, where the symptoms of pneumonic plague resembled influenza59 and occasionally the two accompanied one another.60 Yet no historian or medical researcher has dared to investigate further these possible connections, and few have suggested other alternatives.61	21
Even if this disease had been intercurrent with other diseases or triggered them, as some have speculated to resolve the discordance between what the sources say and what the epidemiology of modern bubonic plague may demand,62 the total absence in the documents or from archaeological evidence of any prior or accompanying spread of the disease among rats must be explained.63 Not only in England and Scotland, where rats existed (even if in insufficient numbers for an epidemic of plague64 ), historians have insisted that this disease was bubonic plague in areas where no evidence of rats appears for the late Middle Ages, as well as in arctic winters, where the spread of modern bubonic plague in epidemic proportions is impossible.65	22
To resolve the inconsistencies past and present, scholars such as the bacteriologist J. F. D. Shrewsbury questioned contemporary accounts rather than the disease. He reasoned that England could not have possibly possessed the population densities of people or rats to sustain a bubonic plague with the massive mortality figures claimed by chroniclers or shown by the replacement rates of the clergy.66 Yet instead of challenging the bubonic plague as the root disease, he dismissed the sources of England's late medieval demographic history. From the biological "laws" of modern plague, he concluded that nowhere did more than 20 percent of the population perish, and for England as a whole, as few as 5 percent died in 1348–1349. Further, he argued, the Black Death, along with subsequent plagues, must have been a disease of towns, despite evidence to the contrary from archaeology and from bishops' and manorial rolls. Some of the highest counts of mortality anywhere come from rural areas such as those around St.-Flour (Auvergne) and in Cambridgeshire, where as much as 76 percent of populations died in the Black Death.67	23
Robert Gottfried questioned the accuracy of Gabriele de Mussis's account of the plague's spread in 1347, when soldiers of the Golden Horde lobbed infected bodies into the besieged Genoese trading port of Caffa on the Black Sea. He rightly pointed out that modern bubonic plague does not spread from dead bodies but requires a rat flea to ingest large concentrations of the bacterium from a diseased rat and afterward to bite a human, regurgitating the bacillus into the human blood stream. But from his knowledge of bubonic plague, Gottfried chose to dismiss the chronicle rather than question what the disease may have been.68 Finally, Ole Jørgen Benedictow has argued against the general consensus that plague in Nordic countries was pneumonic, by pointing out that even in its airborne form modern plague is not highly contagious. Instead of rejecting or questioning the disease's identity as modern plague, however, he turned to a more unlikely solution, especially for the colder climates of Scandinavia, arguing that it was bubonic plague (even though none of these Nordic sources describe buboes) with secondary pneumonic complications, as though secondary pneumonic plague were more contagious than primary pneumonic plague (which it is not).69	24
Let us return to the supposed "certain" signs of the two plagues—the buboes. Do the two periods of plague match so "unmistakably" as scientists and historians continue to claim? Chroniclers, storytellers, poets, and doctors of the later Middle Ages described swellings as large as onions but also pointed to smaller "carbuncles, rashes, freckles, scabs, and other similar things," which preceded, accompanied, or followed the telltale boils.70 This additional complication of the late medieval plague is found even in that passage most often cited in support of the Black Death's identity as bubonic plague, that of Giovanni Boccaccio: "From the two areas already mentioned [the groin and the armpit], the aforementioned deadly gavòcciolo would begin to spread, and within a short time would appear at random on every part of the body. Afterwards, the illness would change with the appearance of black or blue spots (macchie nere o livide) forming on their arms, thighs, and other parts of the body, sometimes large and few in number, at other times tiny and closely spaced."71	25
The largest repository of clinical descriptions of plague after the discovery of the bacillus comes from the first Bombay Report in 1896–1897, conducted by Brigadier-General W. F. Gatacre. Twenty-seven hospitals in and around Bombay City submitted reports, and seven classified their clinical data according to the positions and number of plague boils that formed on their patients.72 Of 3,752 plague patients admitted to these seven hospitals, 2,883 (or 77 percent) developed plague boils. Of these, less than 6 percent had more than a single boil, and not in a single case did spots, blisters, or rashes spread all over the body. This pattern remained much the same when plague spread to Europe at the beginning of the twentieth century. Of thirty-eight hospitalized cases in Glasgow in 1900, none showed spots spreading over the body, and only two had more than a single boil.73 Later editions of Manson's Tropical Diseases note that the spread of "carbuncles," though rare, has been known to accompany the formation of plague boils; the latest case it cites, however, comes from the London plague of 1665.74	26
Nor should we assume that Boccaccio's description of pustules was poetic invention aimed to heighten the horror of plague. For the second plague in Wales in the 1360s, the Welsh poet Llywelyn Fychan75 described a similar course: after the "swelling under the armpit, grievous sore lump" came "the shower of peas," "seaweed scales, a grim throng, berries, it is painful that they should be on fair skin." More prosaically, other fourteenth and early fifteenth-century observers—the Franciscan friar of Messina, Michele da Piazza, the Piacentine Giovanni de Mussis, Giovanni of Parma, a canon at Trent, the Saint-Denis chroniclers of Paris, Marcha di Marco Battagli of Rimini, the chroniclers of the Dominicans of Florence (Santa Maria Novella), the Florentine merchant Giovanni Morelli, the compiler of an obituary in Friuli, a chronicler of Split on the Dalmatian coast, a monastic chronicler of Neuberg in southern Austria, and the Englishman Geoffrey le Baker—described the same pustules, antrachi, or spots spreading over the bodies of plague victims.76 When plague arrived at Catania in October 1347, Michele da Piazza distinguished between antrachi (pustules) and the "glandule" "as big as goose eggs," both of which spread over the body.77 Geoffrey le Baker and Giovanni Morelli maintained that, of the two signs, the smaller carbuncles were the more deadly, giving little hope of survival.78	27
In plague tracts, doctors went further in describing and classifying these pustules by size, color, and type. The distinctions were important for their treatments. The famous doctor Giovanni da Santa Sofia, a professor of medicine at the University of Padua, wrote a tract for the town council of Udine in 1367, advising that plague boils be treated with a plaster of pig fat, but for the smaller antraci and carbuncles, he recommended a plaster made from pigeon dung (de stercore columbino) because of the spots' more "vehement heat."79 Like the chroniclers, the doctors found the smaller spots the more deadly.80	28
Further discrepancies emerge when comparing the positions of the plague boils. With modern bubonic plague, between 57 and 75 percent of the buboes form in the groin, because fleas, although they can jump a hundred times their own height, usually reach no higher than the shins and most often bite around the ankles.81 Thus the first glandular node met by the multiplying bacillus is in the groin. Yet not a single late medieval doctor or chronicler privileged the groin as the place where the medieval bubo most often formed, not even Boccaccio and a handful of others who pointed to the groin and the armpits. Nor were these the only sites for the swellings. Doctors, chroniclers, and plague miracle cures often described them in non-glandular areas—on the shins, the back, the face, on arms, and under the breasts. With modern plague, such formations are extraordinarily rare: only fifteen of the plague boils from the 2,886 patients in Bombay in 1896–1897 were located outside the lymph nodes (0.05 percent).	29
In addition, the late medieval boils' pride of place was in neither the groin nor the armpits, as historians now claim. For the plague of 1361, the chronicler of Parma described them as forming in only one general area—"on the neck, under the ears, that is near the throat."82 In counseling where to let blood from plague patients, doctors were especially attentive to the positions of the boils. Almost without exception, they saw them growing in three glands—the neck, the armpits, and the groin—and began their prescriptions by turning first to the neck, if they did not form there, then to the armpits, and lastly to the groin.83 From thirty-eight miracle cures between 1348 and 1500 found scattered through the Acta Sanctorum that indicated the place of the plague boils, more are found in the neck (fifteen cases) than anywhere else. Finally, the Lucchese doctor Iacopo di Coluccino has left us a rare, if not unique, source for the care of plague patients before 1450. Slipped in his diary (ricordanze) was a two-page insert (cedole) with his clinical notes on seven plague patients he attended twice daily during the plague of 1373. Three of the seven formed boils; all of them were in the neck or behind the ears; none were in the armpits or groin.84 Although small in number, the cases corroborate the impressions gained from the doctors' tracts and the miracle cures.	30
Similarly, the symptoms of the two plagues do not agree as well as historians would like to think. They have seen in the Black Death's Janus face the pneumonic and bubonic phases of the modern plague (even if in modern times the bubonic almost invariably precedes the pneumonic and not vice versa as in 1347–1349). This duality has been invoked to resolve the enigmas of the absence of a prior spread among rodents, the speed of infection, and the disease's rapid movement across Europe and Asia, which can be explained only by person-to-person transmission.85 Most important for this identity has been Guy de Chauliac's description of the plague in Avignon in 1348:	31
The plague (mortalitas) began with us in January and lasted seven months. It had two phases (modos). The first was for two months with continuous fever and the spitting of blood, from which the victims died within three days. The second lasted for the remainder of the period, was also with continuous fever, and abscesses and carbuncles formed in the extremities, namely in the armpits and the groin. These victims died within five days. The disease was extremely contagious, especially with the spitting of blood, so that one caught it from another, not only through close proximity but also through receiving a glance from another. As a consequence, people died without assistance and were buried without priests.86
The passage does not fit the bubonic/pneumonic paradigm, nor does it resolve the problem of the rapid spread of bubonic plague or the "second phase" described by Guy de Chauliac. First, in the twentieth century, septicemic and pneumonic plagues (which kill so fast as not to produce buboes) reached epidemic proportions only in tropical zones such as Ceylon87 or near Arctical ones such as in Northern Manchuria, not in temperate zones such as Western Europe or even in the subtropics of China, India, and Latin America. Second, those stricken with the highly virulent pneumonic form of modern plague rarely survive for more than twenty-four hours,88 not three days as reported by Guy or as with one of Iacopo's plague patients in 1373, who spat blood continuously for four days and certainly had had the disease before coming under Iacopo's care,89 or the eight days reported by doctors in Rome for a plague with only pulmonary symptoms in 1424.90 Further, while a number of medieval chroniclers and doctors can be found who described the dual symptoms of plague—skin disorders with the spitting of blood—Guy was unique in separating the two into two distinct seasons. The others described them as concurrent. In Iacopo's patient log of 1373, bubonic and pneumonic patients became ill at the same time, even within the same families.	32
More problematic, Guy de Chauliac's description of a winter or pneumonic phase followed by a late spring or summer bubonic phase does not help to explain the plague's rapid spread and high mortalities either in 1348 or for the later epidemics. Throughout the warmer Mediterranean zones, where deathbed testaments, necrologies, and burial records survive in large numbers—Florence, Arezzo, Perugia, Siena, Bologna, Orvieto, Rome, Barcelona, Valencia,91 Millau (southern France), Perpignan92 —plague spread rapidly not in winter but at the hottest point of the year, consistently peaking in June or July (see Figures 1–11). The only exception to this Mediterranean pattern comes from Marseilles in 1348, when testaments reached their apex in March.93 From his vantage point in the second decade of the fifteenth century, the Florentine Giovanni Morelli left advice to his future heirs on how to defend against plague, seeing the plague's seasons as predictable: "in the winter before a plague you will hear some whispers of plague in the surrounding countryside [contado] or on the periphery of our territory, and it would be correct to assume that the disease must also be somewhere in Florence. And if you know this in February, people will begin to know of it within the city. [But] deaths from the plague will mount in July and peak by the middle of July."94	33
Bologna, 1348 City Testaments     Figure 1     Orvieto, 1348 Deaths of lay brothers Figure 2     The Plague, 1348: Siena Figure 3     The Plague 1348: Arezzo Figure 4     The Plague, 1348: Florence Figure 5     The Plague, 1348: Perugia Figure 6     The Plague, 1348: Six Cities Arezzo, Assisi, Florence, Perugia, Pisa, Siena Figure 7     The Plague, 1348: Bologna Figure 8     Rome, 1348 Testaments Figure 9     Barcelona: Vaant Benefices, 1348 Figure 10     Millau (Aveyron), 1348 Plague Testaments Figure 11     Number of New Testaments: Six Cities Arezzo, Assisi, Florence, Perugia, Pisa, Siena Figure 12
The first burial records for entire city populations during plague time—those for Arezzo in 1390 with 1,085 deaths and those for Florence in 1400 with over 12,000—illustrate the soundness of Morelli's advice; a few cases may have sputtered in late winter or early spring, producing a slight rise in these cities' normal levels of mortality, but the explosion awaited summer. In March 1400, Florence's mortalities increased from an average of around 125 deaths to 164; in June, they soared to 2,697, then peaked in July with 5,005 and fell in August to 1,947.95 This pattern persisted;96 in 1461, Pope Pius II named the plague "that summer contagion."97 In contrast to the highly contagious summer plague of the later Middle Ages, the warm weather bubonic plague of the twentieth century, despite its virulence, is "one of the least infectious of all epidemics" because of the complexity of its transmission, its reliance on rats and fleas.98	34
On first impression, the striking seasonal regularity of plague in late medieval Italy might suggest that it was the same as modern plague. In late nineteenth and early twentieth-century China, India, and other subtropical places, plague recurred in a particular place with remarkably seasonal regularity.99 Its window of opportunity must fit within the narrow limits of humidity and temperature in which the fertility cycle of rat fleas (principally X. cheopis) revolves. Such conditions are most favorable at warm but not hot temperatures (between 50 and 78 degrees Fahrenheit) and high humidity.100	35
The seasonal peaks of deaths in late medieval plague years found from wills, necrologies, and burial records chart an even more consistent seasonality for Mediterranean zones than that found for India in the first decades of the twentieth century. In India, the plague pattern was bi-modal, occurring either in spring or autumn, punctuated abruptly by the summer's heat. But was the late medieval summer consistency of plague indicative of modern bubonic plague? Historians have failed to point out that the dry and hot summers of Rome, Florence, Perugia, Bologna, Valencia, Barcelona, or Millau are hardly ideal for the rat flea, X. cheopis, and even less so for Europe's most common rat flea, C. fasciatus.101 Nor has global warming changed these matters; indeed, average temperatures have been estimated at +1 degrees Celsius hotter in the fourteenth-century zones south of Germany than in the 1970s.102	36
As found in India, the combination of dryness and high temperatures limits flea fertility, cuts short "the life of free-wandering fleas," hampers the bacillus's survival, and curtails its infectivity.103 By high temperatures, the plague commissioners meant ones above 78 degrees Fahrenheit.104 Above this threshold, "plague does not maintain itself in epidemic form" even with favorable levels of humidity.105 Despite great differences in winter temperatures, the average daily high temperatures in July are higher in Florence (89 degrees Fahrenheit) than in Bombay City (85 degrees Fahrenheit).106 Even more astounding, the peak months of plague in the later Middle Ages (June and July) are the driest months of the year. Correspondingly, they are also the very months when flea life in cities such as Florence or Marseilles reaches its nadir.107 Reflecting these conditions, the flea month in Italy and the Mediterranean more generally is September and October,108 after the rains and the cooling off at the end of the summer.109 Thus the only bubonic plague in Italy observed by Robert Pollitzer in his survey of twentieth-century plagues, which occurred at Taranto in 1945, spread between September and November.110 Yet none of the fourteenth or early fifteenth-century plagues charted by the death records for Barcelona, Valencia, the cities of central Italy or southern France began or peaked in September. By then, all of them had already subsided, and, in most of these, mortality levels had even returned to normal.111	37
A second epidemiological feature that distinguishes the late medieval from the twentieth-century plague is its cycle of recurrence. Before 1450, plague rarely hit a locality two years running, at least in epidemic proportions, and the interval separating plagues ranged between five and fifteen years (see Figures 12–16). By contrast, once modern plague flares up, it remains for the next eight to forty years (as in the case of India), with regular yearly bouts, before mysteriously disappearing.	38
Burials, 1335-1430 Among the laity at San Domenico, Siena Figure 13     Dominican friars of Florence Plague-year deaths, 1348 to 1437 Figure 14     Orvieto: Confraternity of San Francesco Figure 15     Bologna: Plague Years Testaments: Libri Memoriali Figure 16     Plague in India, 1897-1907 Figure 17     Plague Mortality in India 1939-1947 Figure 18
Third, the trajectory of the fourteenth and fifteenth-century plague mortalities differs from the trends of modern plague. Death tolls from the latter (even after effective preventive rat-proofing and health measures have been implemented) do not decline progressively. Instead, annual mortalities first rise for five to ten years, then jump erratically from year to year before falling. Such were the mortality patterns in India from 1896 to 1907 and from 1939 to 1947 (see Figures 17 and 18), in Vietnam in the 1960s, in Thailand from 1944 to 1952, and in other places Pollitzer charted for the twentieth century.112 These trends reveal the absence of any natural or acquired immunity against Yersinia pestis among humans,113 and without it, scientists have yet to discover an effective long-term vaccination against modern plague.114 Unlike most infectious diseases, in terms of case or mortality levels, it does not matter whether modern plague hits a "virgin-soil" population or not. The downturn depends on rats, not humans, acquiring immunity.115	39
By contrast, the figures given by chroniclers and doctors and drawn from late medieval wills, necrologies, and burials show plague mortalities declining sharply over the Black Death's first hundred years, characteristic of a disease in which pathogen and host are rapidly adapting to one another. Having survived four plagues, Raymundus Chalin de Vivario, papal doctor at Avignon, looked back over his plague experience: in 1348, two-thirds were afflicted and almost all died; in 1361, half the population caught it and few survived; in 1371, only one tenth were sick and many survived; in 1382, only one twentieth of the population became sick and almost all survived.116 Although Raymundus's retrospective appears overly optimistic, the trends from testaments and burials trace a similarly progressive, long-term decline in the plague's mortality, at least until around 1450. Surviving testaments taken from six cities in Tuscany and Umbria (Arezzo, Assisi, Florence, Perugia, Pisa, and Siena) declined from 340 in 1348 to less than three-quarters that figure in 1363 (241), to less than a third in 1374 (102), to a fifth in 1383 (71). And for no plague of the first quarter of the fifteenth century did the number of deathbed testaments exceed the 1383 number. For Dominicans born in the province of Florence, the decline in mortality over the first three plagues was even steeper. While the plague of 1363 claimed a third of those friars killed in 1348, the third plague of 1374 claimed little more than a twentieth (5), and after 1400, no plague killed more than that fraction.117	40
The records of the laity buried at the Dominican cemetery, Camporegio, in Siena, on first observation appear to deviate from the patterns traced above. Here, the peak death rate came in 1363, not 1348. But the reason for this discrepancy stems from the cessation of records in 1348 caused by the pervasive fear and overwhelming magnitude of the task faced by the friars as well as by the civil authorities. As Boccaccio and numerous chroniclers lamented, fathers abandoned sons, wives husbands, and sons fathers, resulting in mass burials without proper funerals. By the end of June, at the peak of the plague, the Sienese burial records cease altogether and do not resume until the plague had abated in August. Yet, according to Siena's principal chronicler, Agnolo di Tura, the plague raged during the three summer months, when he claimed three of every four in Siena died. In the summer, the chronicler was forced to bury his five children with his own hands because no one would assist him.118	41
With later plagues, civil and religious authorities adjusted to problems of the deadly contagion and the sudden increases in burials. Institutions such as the Florentine Grascia recorded and regulated burials across all the city's parishes. In Siena, with the plagues after 1348, the Dominicans even added new information to their burial ledgers, such as the addresses of the dead, perhaps in an attempt to understand the plague's spread. Yet, despite this greater care in record keeping, after 1363 burials and other death documents show a steep decline in the plague's triumph over life.	42
Did these declines in mortality simply result from a general decline in population? Quick rises in fertility compensated to some extent for the population losses,119 and, more important, immigrants from the countryside rushed to cities (where these death records are found) to realize new social and economic opportunities. In one place—Florence—where sufficient figures on population were taken and survive, the urban population showed a remarkable capacity to rebound after successive strikes of plague, at least through the fourteenth century. First, its numbers may have dropped from as high as 120,000 before the Black Death to around 40,000 immediately afterward. (The tax surveys [estimi] of 1352 and 1355 numbered around 10,000 households.) Yet, on the eve of the third plague of 1374, the chronicler Stefani put the population of Florence at 60,000 or more. The city responded again with remarkable speed to the losses incurred from this third plague. By the tax records of 1379, its population tallied 13,779 households. Given a household multiplier of around four (slightly less than in 1427), Florence had recouped most of its losses within five years. After the fourth plague of 1383 and on the eve of the fifth of 1400, Florence's population once again stood at 60,000.120	43
In addition, the plague stimulated will writing in Tuscany and Umbria, from the rich down the social hierarchy. In Florence, wills per annum increased threefold after the Black Death and in Tournai fourfold, despite shrinking populations in both places. Similarly, the demand to be buried in Siena's Dominican cemetery rose in non-plague years in tandem with the rising prestige of the Dominicans in post-plague Siena, as illustrated in the pious choices of the laity in their last wills and testaments.121 To control for these demographic shifts and counterbalancing tendencies, I have charted the plague figures as ratios of the preceding intervals of non-plague years. By these ratios, the steady downward thrust of plague mortality is even more striking than that shown by the raw figures (see Figures 19–20). From the testamentary evidence of the six Italian cities, plague mortality relative to non-plague years was less than a quarter of 1348's onslaught by the third plague (1374) and one-sixth the ratio by 1400. From the Sienese burials, 1374's toll amounted to half the relative mortality of the preceding plague of 1363, and the last plague the friars recorded, that of 1430, killed only a tenth the numbers taken in 1363 relative to previous years of non-plague deaths.	44
Testaments: Six Cities Plague years as a ratio of non-plague years Figure 19     Sienese Plague Burials Plague mortality as a ratio of non-plague mortality Figure 20
Our best example comes from the citywide lay confraternity of San Francesco in Orvieto. In addition to an obituary of all its members from 1337 to 1398, it kept a matriculation list over the same time span.122 In 1348, 109 members or half the brotherhood died, amounting to thirty-six times the average per annum mortality since the confraternity's foundation. With the second plague of 1363, deaths rose above any previous non-plague year (22) but were only a fifth the 1348 toll. By the third and fourth plagues, 1374 and 1383, the numbers of deaths (8 and 9) tumbled to just over one-twentieth the plague's first strike (see Figure 15). For this community, we can be certain that the decline did not simply arise from a progressively shrinking population exposed to death. In addition to being an extraordinary year for deaths, 1348 was equally unusual for attracting new entrants: while 109 died, 110 joined. No doubt the confraternity's attraction hinged on its role in providing for the spiritual and corporeal needs of the dead, but it was not a matter of the dying signing up on the spot to ensure themselves the proper sacraments and burial. The new entrants did not boost the confraternity's mortality rates. Forty-four percent of them as opposed to 54.8 percent of the previously enrolled members died in that year.123 Moreover, the confraternity's popularity continued through the century, with more members joining after 1349 than before; thus the decline in mortalities relative to the community's population was even steeper than the raw death figures chart.	45
Infectious Diseases: England and Wales Figure 21
Another characteristic of the adaptation and immunity of late medieval population was the radical change in the age structure of the victims. The records of Siena are the only ones I know to cover the burials of the laity across the plague experience from the Black Death of 1348 to the fifteenth century. Here, we witness a remarkable transformation. Of 136 buried in the Dominican cemetery in 1348, only 12 were identified as children.