CHAPTER I. PREVALENCE OF DOCTRINE OF ATMOSPHERIC CONTAGION, INJURY TO PATIENT, ATTENDANTS AND VISITORS. Atmospheric contagion, to which public attention is directed, has been regarded for many ages as the cause of a great proportion of the pestilence incident to the human race; and, at the present day, most of the diseases which are wont to be widely spread, and to be very mortal, are usually considered as depending on that agent, both by the unprofessional and the medical world: indeed, so extended has been thought its sphere of action, that it is suspected to be operating in almost every case that occurs, of those diseases which usually attack many at the same time; and, in nearly every instance, its existence is positively inferred, where previous cases can be shewn to have been prevailing, though at the distance of several miles. It is a fact familiar to many, that, on the occasion of the late prevalence of Cholera Morbus in the years 1831 and 1832, that infection, through the medium of the air, was considered the most common cause of the propagation of that scourge; and every mother is taught to regard every case of scarlet fever, common fever, hooping-cough, and many such disorders, as a very centre of infectious air that possesses qualities subversive of the health of her children. Ordinary conversation, too, marks well the common belief in the positive injury that agent inflicts. In general, it seems a matter quite out of the question to suppose, that the patient may have got his sickness from the operation of other and distinct causes, as is sufficiently evident from such common questions as these, “Had he visited any person ill of the same complaint?”—“Where, and from whom, did he get the infection?” and likewise from the ordinary replies, “He got it from a friend, at whose house he called to inquire after his health,”—“He caught it when passing through a street in which a person lay ill of the same distemper.” Such inquiries and replies are made not only by the public, but by the medical profession also, who are, in general, sufficiently satisfied if such answers and solutions as those above be given. Were it necessary to say more to prove the important position infection holds as a cause of disease, and as the chief instrument of its propagation, references might be made to thousands of instances, narrated, too, on medical authority, where whole visitations of pestilence have been attributed to its operation, and volumes might be filled with the most skilful artifices, devised, and actually carried into execution, to deprive the air of its invisible poison; but these steps are deemed unnecessary here. The belief in the doctrine of atmospheric contagion is hurtful to the patient by its direct influence on his mind, and the gratification of his wishes.