When the Black Death arrived in England in summer 1348, it had already hit China, middle Asia, the Crimea, and Sicily, and had begun moving inland to the rest of continental Europe. The death rate varied from region to region, but it is probably fair to say that it ranged from about 12% to 66% of the population. Some evidence points to the Black Death being the plague, a fever caused by the bacterium Yersinia pestis; while other evidence suggests it was viral in origin. Regardless of the cause, it was extremely infectious and caused upheaval for decades everywhere it hit.
Bernard de Gordon, in his Lilium medicinae, enumerates some signs of impending plague in the chapter entitled “Pestitential fevers.” Each chapter in Lilium is divided into 6 sections: the first included the definitions, names, and types; the second, the causes; the third, the diagnosis; the fourth, the prognosis; the fifth, the treatment; and finally, the sixth – the clarification. The following is a loose translation of a 1551 version of Lilium, from the second section of “Pestilential fevers.”