In describing the symptoms arising from the derangement of the group of faculties last under consideration, namely, those termed moral, and with which man is specially endowed, as contrasted with the lower animals, it might have seemed natural to detail those morbid mental phenomena, which Prichard and others have so much dwelt upon when treating of moral insanity. But such a perverted condition of the moral sense is so almost invariably indicated, and often only discovered by the activity of the animal propensities, that it is more convenient to treat of it under the third class of mental disorders. It is likewise more consistent with our adopted principle of classification, which consists in referring each mental disorder to that group of faculties, the affection of which is essential to its manifestations. In homicidal mania, the animal propensities are of necessity called into action, whether the homicidal act be the result of their diseased action, in association with a healthy condition of the higher sentiments, or of their normal action when associated with, and therefore uncontrolled by, a state of the moral sense rendered powerless or feeble by disease; be it congenital or acquired, or the result of functional disorder or structural changes. We usually become cognizant of diseased mental conditions by positive, not by negative, symptoms; some overt act or explosion of passion will, in general, be the first proof of such disease of the moral sentiments, as involves their occlusion or inertness, when they ought to be in exercise. Should the disease be of such a nature as to increase the activity of these faculties, then we have an exhibition of religious excitement or ecstasy, a morbid condition already treated of.