and when we observe what a severance may exist between the so-called organ of any sense or faculty and the operation of the sense or faculty; and how infallibly ideas and emotion may be generated, and even beliefs created in minds sane and insane, by certain manipulations of the nerves and brain, we see how innocently this phenomenon may be presented in natural somnambulism. Sleepwalkers have been known in many countries, and treated of in medical records by their physicians, who could not only walk, and perform all ordinary acts in the dark as well as in the light, but who went on writing or reading without interruption though an opaque substance--a book or a slate--was interposed, and would dot the _i's_ and cross the _t's_ with unconscious correctness without any use of their eyes. There is a wide field of inquiry open in this direction, now that the study of the nervous system has been begun, however minute is the advance as yet. IMPORTANCE OF THE SUBJECT. It is needless to dwell on the objection made to the rising hopefulness in regard to the study of Man, and the mysteries of his nature. Between the multitude who have still no notion of any alternative supposition to that of possession or inspiration by spirits, or, at least, intercourse with such beings, and others who fear "Materialism" if too close an attention is paid to the interaction of the mind and the nerves, and those who always shrink from new notions in matters so interesting, and those who fear that religion may be implicated in any slight shown to angel or devil, and those who will not see or hear any evidence whatever which lies in a direction opposite to their prejudices, we are not likely to get on too fast. But neither can the injury lapse under neglect. The spectacle presented now is of the same three sorts of people that appear in all satires, in all literatures, since the pursuit of truth in any mode or direction became a recognized object anywhere and under any conditions. Leaving out of view the multitude who are irrelevant to the case, from having no knowledge, and being therefore incapable of an opinion, there is the large company of the superficial and light-minded, who are always injuring the honor and beauty of truth by the levity, the impertinence, the absurdity of the enthusiasm they pretend, and the nonsense they talk about "some new thing." No period of society has been more familiar with that class and its mischief-making than our own. There is the other large class of the cotemporaries of any discovery or special advance, who, when they can absent themselves from the scene no longer, look and listen, and bend all their efforts to hold their ground of life-long opinion, usually succeeding so far as to escape any direct admission that more is known than when they were born. These are no ultimate hindrance. When Harvey died, no physician in Europe above the age of forty believed in the circulation of the blood;