A PARTICULAR OBJECTIVE of this special issue of The Medieval Globe, “Pandemic Disease in the Medieval World: Rethinking the Black Death,” is to interrogate how scientific and humanistic approaches to plague's histories can enrich and expand one another. Science, we have argued, has developed methods to reconstruct the deep histories of pathogenic organisms in addition to studying them as they exist in the present-day world. At the same time, the humanistic disciplines retain their power to reconstruct human activities that may have contributed to Yersinia pestis's amplification throughout the world and to describe and explain how humans responded to that threat. All disciplines involved in the analysis of the past have rigorous standards of what constitutes evidence and what kinds of interpretations are valid. Multidisciplinary work demands due respect for those traditions.

This short essay offers a lesson in caution. It is a story of error, but also an opportunity to be reminded of the care needed to properly contextualize all our evidence—to be reminded, as L. P. Hartley famously said, that “the past is a foreign country: they do things differently there.” To negotiate this country successfully, we need to learn its language.

The image on the following page (Plate 3) has been reproduced in the past decade in a variety of popular media: Wikipedia, pamphlets for sale at tourist sites, the cover of an encyclopedia devoted to the Black Death, an exhibit on the Black Death at the Museum of London in 2012, a NOVAdocumentary, and an essay in one of the world's leading science journals. It even appeared in one of our own publications, inserted by an editor without consultation (Green 2011). It is accompanied by captions such as “monks, disfigured by the plague, being blessed by a priest” or “Plague victims blessed by priest.” Perhaps its most significant use was in Callaway 2011, which was an interpretive essay in Nature accompanying the announcement of the complete sequencing of the Yersinia pestis genome retrieved from the mid-fourteenth-century London Black Death Cemetery, the first pathogen fully sequenced from historic remains (Bos et al. 2011). There, it bore the caption “Historical descriptions of the Black Death have helped link Yersinia pestis with the disease.”