1. When the authority of the ancients is invoked to determine any procedure in medical practice, we must remember that their idea of what constituted disease consisted in the symptoms it manifested. When, therefore, a symptom was diminished or removed, they regarded the means they employed as having diminished or removed the disease. That a blood-letting relieves the pain and dyspnœa in pneumonia is an unquestionable fact. If employed early, it is true the symptoms returned, and the remedy had to be repeated; but if carried out on the fourth up to the eighth day, when, according to the extent of the disease, these symptoms usually subside, and the exudation commences to be absorbed, it appeared to act like a charm. It was then said that the disease was knocked down, or strangulated; and if the patient recovered, however lingering was his convalescence, the value of the remedy appeared to be unquestionable. This idea, it seems, still prevails with some physicians, as we have previously seen that Dr. Sieveking instructed his pupils that he had “knocked down” a double pneumonia by a small bleeding, although the condensation of the lungs—that is, the true disease—still continued. But modern research has demonstrated that there is no relation whatever between the symptoms and the morbid state of the lung, which it is the object of the well-informed physician to remove. It would be easy to show that there are many cases where all the symptoms of a pneumonia have been present, but where a post-mortem examination has proved that there was no inflammation of the lung; and that a still larger number of instances might be cited where fatal pneumonia has occurred without any of its symptoms having existed during life. Such was the unacquaintance of the past race of practitioners with diagnosis and pathology as now understood, that no confidence whatever can be placed on their impressions as to what disorders were or were not benefited by bleeding.