History of the Peloponnesian War

On the city of Athens it fell suddenly, and first attacked the men in the Piraeus; so that it was even reported by them that the Peloponnesians had thrown poison into the cisterns; for as yet there were no fountains there. Afterwards it reached the upper city also; and then they died much more generally. Now let every one, whether physician or unprofessional man, speak on the subject according to his views;

from what source it was likely to have arisen, and the causes which he thinks were sufficient to have produced so great a change [from health to universal sickness]. I, however, shall only describe what was its character; and explain those symptoms by reference to which one might best be enabled to recognise it through this previous acquaintance, if it should ever break out again; for I was both attacked by it myself, and had personal observation of others who were suffering with it.