It is probable that the atmosphere contained foreign and sensibly perceptible admixtures to a great extent, which, at least in the lower regions, could not be decomposed or rendered ineffective by separation. In 1348 an unexampled earthquake shook Greece, Italy, and the neighbouring countries. During this earthquake the wine in the casks became turbid, a proof that changes causing a decomposition of the atmosphere had taken place. "The insect tribe was wonderfully called into life, as if animated beings were destined to complete the destruction which astral and telluric powers had began."
"The corruption of the atmosphere came from the east, but the disease itself came not upon the wings of the wind, but was only excited and increased by the atmosphere where it had previously existed."
"The most powerful of all the springs of the disease was contagion; for in the most distant countries, which had scarcely yet heard the echo of the first concussion, the people fell a sacrifice to organic poison, the untimely offspring of vital energies thrown into violent commotion."
"After the cessation of the Black Plague, a greater fecundity in women was every where remarkable, a grand phenomena, which from its occurrence after every destructive pestilence, proves to conviction the prevalence of a higher power in the direction of general organic life."
In the article Contagion, of the Essay, Sweating Sickness: "Most fevers which are produced by general causes, propagate themselves for a time spontaneously." "The exhalations of the affected become the germs of a similar decomposition in those bodies which receive them, and produce in these a like attack upon the internal organs, and thus a merely morbid phenomenon of life, shows that it possesses the fundamental property of all life, that of propagating itself in an appropriate soil. On this point there is no doubt, the phenomena which prove it have been observed from time immemorial, in an endless variety of circumstances, but always with a uniform manifestation of a fundamental law."
Mead, in his Essay on the Plague, makes many observations of great interest and worthy a physician of eminence; and where, in recent times, shall we look for any more definite information concerning the causes of pestilences? It is not a little singular that at the time this book was published, it was read with such avidity that it went through seven editions in one year.[[22]] From this circumstance we may gather that the public generally took a lively and proper interest in a subject that was not only of domestic, but national importance. Whether this interest was stimulated by the fact that the work was written expressly by order of the
government, it is now impossible to say, at any rate much credit is due to the Lords of the Regency for having placed so important a duty upon one so thoroughly and in every way so duly qualified for the task as Dr. Mead. It had been well if some of the advice given at that time, as means of protection against the Plague, had been applied and put in force during the late visitation of epidemic Cholera, for, however the minds of some may be convinced of the non-contagiousness of Cholera, there are many who hold a different opinion, and all will acknowledge, that if not strictly a contagious affection, it is clearly proved to be capable of being carried from place to place, or to use Dr. Copland's words, it is "a portable disease." But this is not the place to discuss the subject of contagion, allusion will be made to it hereafter. To return, Mead's expressions are singularly illustrative of the vital power possessed by the germs of disease; he says, "There are instances of the distemper's being stopt by the winter cold, and yet the seeds of it not destroyed, but only kept unactive, till the warmth of the following spring has given them new life and force. His confession as to the hidden cause of the disease, is worthy transcribing: "We are acquainted too little with the laws, by which the small parts of matter act upon each other, to be able precisely to determine the qualities requisite to change animal juices into such acrimonious humours, or to explain
how all the distinguishing symptoms attending the disease are produced."[[23]]