The question that remains is the connexion, in pathological theory, between the bubo-plague and the corruption of the unburied dead or of the imperfectly buried dead. Some such connexion was the rumour of the time, before any scientific theory can well have existed. Also the factor in question was undoubtedly there among the antecedents, if it were not even the most conspicuous of the antecedents. But we might still be following a wandering light if we were to trust the theory of the Black Death to those empirical suggestions, striking and plausible though they be. It is not for the Black Death only, but for the great plagues of the Mohammedan conquests, which preceded the Black Death by many centuries and also followed that great intercurrent wave until long after in their own strict succession, for the circumscribed spots of plague in various parts of Asia and Africa in our own day, and above all for the great plague of Justinian’s reign,--it is for them all that a theory of bubo-plague is needed. A survey of the circumstances of all these plagues will either weaken or strengthen, destroy or establish, the theory that the virus of the Black Death had arisen on the soil of China from the cadaveric poison present in some peculiar potency, and had been carried to Europe in the course of that overland trade at whose terminus we first hear of its virulence being manifested. The theory of the origin of the plague-virus from the corruption of the dead was a common one in the sixteenth century. It was held by Ambroise Paré among others, and it was elaborately worked out for the Egypt of his day by Prosper Alpinus, physician to the Venetian Consulate at Cairo towards the end of the same century. But the most brilliant exposition of it, one of the finest exercises of diction and of reasoning that has ever issued from the profession of medicine, was that given for the origin in Egypt of the great plague of Justinian’s reign by Etienne Pariset, secretary to the Académie de Médecine and commissioner from France to study the plague in Syria and Egypt in 1829[296].