Besides this, we are, in a measure, prepared to foretell the probable course of a disease, and can, therefore, in many cases, adopt anticipatory measures, while in all we will be guarded against the error, so often committed, of ascribing to the remedy used the so-called “_aggravations_,” which are often only natural symptoms of the unchecked and, perhaps, entirely uninfluenced morbid process. Such knowledge serves thus, by purifying our experience, to guard us against self-deception, and to prevent us from misleading others by reports of cures of diseases existing only by virtue of a false diagnosis. A knowledge of pathology, furthermore, places in our hands a thread which can guide us through the labyrinth of our vast materia medica, and which enables us, from the myriad of symptoms, to eliminate the non-important ones. It shows us the “bearings” of the medicines and their various specific ranges, thus materially facilitating the choice of a remedy. Again, medical science is virtually based upon pathology, and we see, therefore, how important, nay, how absolutely necessary, to the progress of the former is the study of the latter. The practice of medicine as an art can never be advanced knowingly by those who neglect its cultivation as a science. While each one may practice the art according to his own convictions, true medical science stands above all the belittling, bigoted prejudices of the schools. Here, every one claiming the name of an educated physician can and ought to work. The wild vagaries of former ages, when philosophy set up purely theoretical views, under which observed phenomena were compelled to arrange themselves, have warned the present age to be guided solely by sober and exact observations and investigations; and it needs no proof that, in the advancement of our knowledge of disease, these are best accomplished by frequent post-mortem examinations, which thus become a necessary adjunct to a proper study of pathology. In all cases of interest, therefore, the physician should feel it a duty which he owes to himself and the profession at large, to seek permission to make a post-mortem examination; but in order that the fullest benefit may be derived from the same, he must know how to look for what he is in search of, and how to recognize it when found. To furnish this knowledge is the object of the following pages, to which we herewith introduce the reader. PRELIMINARY CHAPTER. INSTRUMENTS AND GENERAL DIRECTIONS. =The Post-mortem Case=, as prepared by the instrument makers, will be found to contain, usually, the following instruments: [Illustration: [Scalpels]] 1. A set of ordinary dissecting scalpels, four or five in number, and of graduated sizes, including one heavy cartilage knife. [Illustration: [Knife]] 2. A brain knife with a long blade, for slicing the brain. [Illustration: [Chisels]]