Prologue • 5Still, Allin enjoyed many skills and passionately followed his favorite pursuits
of astrology, alchemy, and medical diagnostics. He would soon turn his tal-
ents to understanding plague, the disease everyone feared most.^6
The people in these pages, along with thousands of their countrymen, expe-
rienced plague firsthand. It did not arrive as a totally unknown disease, how-
ever. The ancient Greeks had called any human scourge plague,from the
wordplaga,meaning a blow. The Romans added the Latin word,pestis—
pestilence. Before long plagueandpestilencebecame interchangeable. When a
disease caused the calamity, the outbreak was called an epidemic,from the
Greek epi(among) and demos(people). Hebrew scriptures narrated wide-
ranging plagues inflicted on Pharaoh for keeping the Israelites in slavery and
spoke of a three-day plague suffered by King David’s subjects for his blas-
phemy of numbering God’s chosen people in a census. The Greek historian
Thucydides wrote dramatically about a hugely mortal “Plague of Athens” in
430 – 427 b.c.,from which he personally suffered.
It is hard to tell what diseases caused epidemics like the one at Athens.
Greek medical authorities, from Hippocrates (in the fifth century b.c.) to
Galen (third century a.d.), defined individual maladies largely by symptoms
and sorted them into chronic, endemic, and epidemic groups. This classical
tradition continued to shape medical terminology well into the eighteenth
century. But along with the continuing use of the words plagueandpestilence
to describe all epidemics, eyewitness observers began to apply the words to
human morbidity and mortality associated with some bodily signs and
symptoms that kept recurring.^7
Modern histories of medicine distinguish three historical periods of re-
peated plague epidemics exhibiting these traits, calling them pandemicsfrom
the Greek pan(all) and demos(people).^8 The three plague pandemics were
Justinian’s Plague, which began under the late Roman Emperor Justinian in
a.d. 541– 544 and kept returning for two centuries; a second pandemic that
started with the Black Death of 1347 – 52 and continued in Europe with fresh
outbreaks well into the eighteenth century; and a third pandemic that af-
fected five continents between the late nineteenth century and the mid–
twentieth century. Since then, the disease has settled into an enzootic exist-
ence among wild rodents in scattered parts of the globe, with occasional
transfers to individuals and sporadic epidemic outbursts among humans
causing a few fatalities.
Apart from the physicians William Boghurst and Nathaniel Hodges, our
protagonists of the Great Plague of London in 1665 knew little to nothing