THE question of the relation of the mental and the corporeal powers has always had a deep speculative interest; but, as science is gradually working it out, it is found to have also a profound practical interest. It is strange that a subject of such fascination, and concerning which so much has been said in all ages, should be so late in its rational elucidation. But, besides the difficulties which spring from its extreme complexity, the inquiry has been perpetually hindered by prejudice and passion. Singular as it may appear, the acquisition of the most important of all knowledge, that of the human constitution by dissection, has been held as a crime until the present generation. The prejudice that led to this result led also to the further result that the most important part of the human system, that which is specially devoted to psychical ends, has been considered last. The early anatomists refrained from dissecting the head for fear of committing impiety, and there remained, long after, a kindred feeling against the analysis and study of the brain. Even when it had been demonstrated, and was admitted by all physiologists, that the brain was the organ of the mind, there still lingered with many a belief that it was a sort of unaccountable, half-superfluous appendage to the body, with no such reason for its existence as was obvious in the case of other anatomical parts. Physiologists might show that it had special relations with the mind, but the students of mental philosophy denied that it was of any importance to them, and proceeded with their inquiries as if it had no existence at all. Buffon described the brain as consisting of a kind of "ignorant mucilage," and the Rev. F. W. Robertson expressed the general metaphysical and theological contempt for it by ridiculing the idea of accounting for mental effects "by a few ounces more or less of the hasty pudding contained within the skull." We are indebted to the phrenological school for having made a vigorous fight in behalf of the claims of the head upon the students of mind, and, whatever may be the imperfections of their scheme, they have certainly cleared away a vast amount of prejudice in the popular mind, and prepared for the consideration of the material apparatus in connection with mental phenomena.
It is now well established that, in the study of mind and character, the physiological organism is not only to be taken into account, but is to be made the basis of investigation. Metaphysical treatises open with a description of the nervous system, even if it plays no part in the subsequent exposition. But, wherever mind is studied with a view to practical ends, it is found necessary not only to admit in a general way the intimate dependence and close interaction of the mental and corporeal systems, but the relations have to be worked out with the utmost detail on both sides. In dealing with abnormal mental manifestations, as in the numerous forms of insanity and the various grades of feeble-mindedness, or with the psychological effects of stimulants and narcotics, or with the development and decline of the mental powers, or with the effects of mental overwork and exhaustion, it is now admitted to be indispensable to start from the nervous system, and to regard mental manifestations as conditioned by its properties and laws. Thus far it is only physicians, compelled