Thucydides (460 BC-395 BC) interrupted his account of the Peloponnesian War to describe the famous Plague of Athens, which occurred at the start of the summer in 430 BC. This description was long considered among the first descriptions of an epidemic. Indeed, whereas Thucydides used nosos, the term plague, which is used by all the translators of his work, is used in the sense of the Latin term pestis, a term with no clear etymology (4), meaning contagious disease, epidemic, or scourge. The description of the Plague of Athens, like that of the Cough of Perinthus by Hippocrates, is an essential text in the philologic and semantic study of epidemics (5) . We must therefore consider, as for Littré's translation, the meaning that translators have assigned to the original description by Thucydides. Thucydides never used the term epidemic that Hippocrates was in the process of establishing. Under the term nosos, Thucydides described a series of clinical signs, which originated in the south of Ethiopia and propagated throughout Egypt, Libya, and then Greece. Thucydides used the words nosos, kakos (evil), ponos (pain), phtoros (ruin, destruction), and loimos (scourge) to describe what his translators call plagues. In her translation of Thucydides' works (6) , published in 1991, in the chapter titled Second Invasion of Attica: the Plague of Athens (the original Greek work had no title), Jacqueline de Romilly translated nosos as disease or epidemic. Similarly, she translated loimos, kakos, and phtoros as disease or epidemic and the list of clinical signs (the original Greek meant "following these things") as symptoms. de Romilly rendered the text more elegant and accessible to 20th-century readers by this translation but gave the words used by Thucydides their 20th-century meaning rather than the meanings they had in the 5th century BC. Herein lies the principal problem of translation.