Infectious diseases may be frightening to contemplate, but in fact human beings have always lived-and died-at close quarters with pestilence, just as they have with war and starvation.
其實自有人類以來，瘟疫、戰爭、飢荒、死亡就是人類的四大敵人，戰爭、飢荒、瘟疫經常伴隨而來，造成人類大量的死亡。