Thucydides gave a reason for describing the plague at Athens, and the reason was not to explain it. Causes were left to others, physician or layman; the historian would set down what the disease was like, so that a person who met it again would not fail to know it. Many centuries later, Boccaccio opened the Decameron with a long account of the pestilence in Florence, explaining to the book's readers that without this review of the past the stories that follow could not be understood. One text announces that it is written for a future recognition. The other announces that it is written as a necessary memory. Both describe diseases whose identity is now disputed.
This article asks a narrower question than which diseases these were. It asks what Thucydides and Boccaccio put on the page that a later reader could use to recognise the disease, and what that material can and cannot carry in the modern disputes over identification. The question can be answered from the texts themselves, which are in the public domain in their original languages and in nineteenth- and early twentieth-century English translations, and which this article reads at length.
Two disputes give the question its stakes. The first concerns Athens. David Morens and Robert Littman read Thucydides's account as epidemiological evidence, attending to the onset, the spread, the attack among those who nursed the sick, the symptoms and the immunity of those who recovered, weighed the many diseases that had been proposed, and concluded that the account does not allow a firm identification (Morens and Littman 1992). Manolis Papagrigorakis and colleagues later reported DNA sequences resembling Salmonella enterica serovar Typhi from the dental pulp of people buried in a mass grave in the Kerameikos at Athens, dated to the time of the plague, and proposed typhoid fever as its probable cause (Papagrigorakis et al. 2006). Beth Shapiro, Andrew Rambaut and Thomas Gilbert replied that the sequences do not place the organism as Typhi with confidence, that the methods do not exclude contamination, and that the cause remains unproven (Shapiro, Rambaut and Gilbert 2006). The second dispute concerns the Black Death. Samuel Cohn argued that the medieval disease's patterns of spread, seasonality and symptoms, as contemporaries recorded them, differ from those of the bubonic plague observed from the 1890s, and questioned the identification of the two (Cohn 2002). Kirsten Bos and colleagues reconstructed a draft genome of Yersinia pestis from teeth of people buried in the East Smithfield cemetery in London, used for the dead of 1348 to 1350, establishing that the Black Death was caused by that organism (Bos et al. 2011).
In each dispute one side reads written description and the other reads material from the dead. What the disputes, as the reading notes describe them, leave to one side is a reading of each text sentence by sentence, in its own order, in its original language as well as in English. That is the gap this article fills. Its contribution is a reading of the two texts as documents of recognition: what the author claims to have seen, what the author reports as said or believed, what the author leaves aside, and what the author offers as a sign. The reading states what the texts commit to and what they do not, and it shows that the two texts are not the same kind of document. Thucydides writes for a reader who will meet the disease. Boccaccio writes for a reader who must be persuaded that the thing happened at all.
Beside each text the article sets a modern record. Skeptron, a history studio in the RISCON family of sites, publishes short records of historical cases written for its platform, and the study from which this article is drawn read eighty-nine of them. Two concern these texts. They are modern summaries, written in Korean and read here in an English translation made once for the study; they are not archival documents, and they add nothing to what the ancient and medieval texts say. What they keep and drop shows which parts of each text a careful present-day reader treats as the evidence.
The placement of the secondary works in this article, and their application to the two texts, are the article's own. The works are described only as far as the study's reading notes describe them.
Section 2 lays out the two disputes and the ideas used to read the texts; Section 3 describes the sources; Sections 4 and 5 read Athens and Florence; Section 6 brings them together; Section 7 concludes.