Excerpt from A Manual of Diseases of the Nervous System, Vol. 1 A classification of Diseases of the Nervous System, at once scientific, exact, and convenient for systematic description, is not at present possible. If we attempt to classify the diseases according to either seat or nature, we are met at once by difficulties which prevent any complete arrangement. These difficulties arise from the fact that many diseases affect more than one part of the nervous system, that the precise seat of other maladies is unknown, and that we are still ignorant of the nature of a considerable number of diseases. A rough division is often made into two broad classes of organic and functional disease. The first class, that of organic diseases, comprehends those in which there is always a visible lesion, manifesting sometimes the morbid process which constitutes the disease, sometimes only the ultimate result of that process. The second class, that of functional diseases, is less definite, comprehending (1) those diseases that consist only in a disturbance of function, and are there fore properly so designated; and (2) many diseases which have this in common with true functional disease, that they are transient and not permanent, and that they are not known to depend on organic changes. But there is also a large class of diseases in which no constant lesion has been discovered, but which are not transient, and cannot well be placed in either of these classes. This simple classification is therefore inadequate. It may be well to consider in what respect it needs alteration to meet the requirements of our present knowledge. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.