History of the Peloponnesian War

It began, by report, first in that part of Ethiopia that lieth upon Egypt, and thence fell down into Egypt and Africa and into the greatest part of the territories of the king.

It invaded Athens on a sudden and touched first upon those that dwelt in Piraeus, insomuch as they reported that the Peloponnesians had cast poison into their wells (for springs there were not any in that place). But afterwards it came up into the high city, and then they died a great deal faster.

Now let every man, physician or other, concerning the ground of this sickness, whence it sprung, and what causes he thinks able to produce so great an alteration, speak according to his own knowledge. For my own part, I will deliver but the manner of it and lay open only such things as one may take his mark by to discover the same if it come again, having been both sick of it myself and seen others sick of the same.