Plague is a satisfactory disease to speak or to write about. Its history may be traced and is fairly well known. But first and foremost, it is spectacular. The mere name of the sickness brings fear and by contrast with “influenza,” which in India destroyed in a few days more lives than the plague in as many years, the word “The Plague” is emotionally colorful. Its biology has been studied and, to a certain extent, its epidemiology has been explained with considerable success. Moreover, the most pessimistic can hardly doubt that, until civilization completely disintegrates, bubonic plague will never cause the havoc it did 500 or even 300 years ago. But, in another sense, the subject appears quite unsatisfactory when after a brief period of enthusiasm the initiated analyzes deliberately the known and unknown in plague. In spite of all the details accumulated in the published records unfortunately read by a relatively few, nobody can answer the great question as to why epidemics or pandemics occur.