As far then as Sacred History conducts us in the enquiry, concerning the causes of pestilences, we gain encouragement in the belief that living germs are the active agents, for in the case of the leprosy, we have evidence of reproduction in connexion with infection, which, if our line of argument be tenable, amounts to demonstration; then, in the other instances of the plagues, by boils and blains, they distinctly bear comparison with the accounts given by profane writers, of the visitations of pestilences on the earth, subsequently to those mentioned in Scripture history.
This leads now to the consideration of recorded facts observed and noted during the various Epidemics in the early and subsequent periods of Man's History, as given by those on whom reliance may be fairly placed.
Setting aside the uncertain information contained in the writings of the Chinese,[[17]] a people whose
progress in the science and practice of Medicine has nothing to commend it (even as it is at the present day) to the notice either of the physician or the historian, unless it be to the latter as a mark of peculiarity both in a social and political point of view,—passing also over the Egyptians, the Arabians, and the Greeks,—and even Hippocrates himself, we are driven to the Romans for any authentic or precise notice of Epidemic Affections. It has been attributed to Hippocrates that he predicted the appearance of the Plague at Athens,
and that when it was introduced into Greece he dispelled it, "by purifying the air with fires into which were thrown sweet-scented herbs and flowers along with other perfumes."[[18]] But little advantage can be derived from enquiries concerning the first appearance of any disease, for the probability of discovering the primary cause is certainly a
hopeless case, if attempted by means of the writings of ancient authors, when it is recollected that with all the science and learning of the ancient Egyptians, the use of optical instruments was not comprised among the paraphernalia of their arts. The knowledge that was limited to the powers of natural vision, where the foundation of knowledge is based upon facts obtained through the aid of that penetrator of nature's secrets, the microscope, offers no advantages to the student of the present day.
To say that a disease commenced in the East and travelled westward, and at length found a habitation and a name in every part of the globe, is no more than to say that disease is coeval with the fall of man. The cause is as much hidden in the region of its birth, as in that where it sojourns for a time. The cause of the sweating sickness was as much a mystery in England as in all the other nations of Europe, which were visited by its devastating power. And these observations apply with as much force to one disease as another; for even our indigenous ague, originating in some places so limited that the shadow of a passing cloud may mark the boundary of its dwelling place, as inscrutably evades our vigilance, with all the appliances that art can bring to our assistance, in endeavouring to evoke its extraordinary properties under the cognizance of our senses.
If we weigh the air which carries the poison, or analyze it by the most delicate chemical tests, or
take the weight of the atmosphere which is charged with it, or if we take the blood which carries the germs of the disease to the tissues of the body, and submit them after the work of destruction is accomplished, to the most rigid inspection, we can but exclaim,
"These are Thy marvellous works!"