Cabanis, in his interesting work, "Rapports du Physique et du Moral de l'Homme," offers the following remarks on this most curious subject: "Sensibility may be considered in the light of a fluid the quality of which is determined, and which, when carried to certain channels in greater proportion than to others, must of course be diminished in the latter ones. This is evident in all violent affections, but more especially in those ecstasies where the brain and other sympathetic organs are possessed of the highest degree of energetic action, while the faculty of feeling and of motion--in short, the vital powers--seem to have fled from the other parts of the system. In this violent state, fanatics have received with impunity severe wounds, which, if inflicted in a healthy condition, would have proved fatal or most dangerous; for the danger that results from the violent action of external agents on our organs depends on their sensibility, and we daily see poisons, which would be deleterious to a healthy man, innocuous in a state of illness. It was by availing themselves of this physical disposition that impostors of every description, and of every country operated most of their miracles; and it was by these means that the Convulsionists of St. Medard amazed weak imaginations with the blows they received from swords and hatchets, and which in their ascetic language they called _consolations_. This was the magic wand with which Mesmer overcame habitual sufferings, by giving a fresh direction to the attention, and establishing in constitutions possessed of great mobility a sense of action to which they had been unaccustomed. It was thus also that the _Illuminati_ of France and Germany succeeded in destroying external sensations amongst their adepts, depriving them in fact of their relative existence." In these phenomena we do not witness miracles or supernatural agency. Enthusiasts are simply maniacs. Like maniacs, their vital endowments are deranged; they lose the faculty of feeling, of reasoning, of comparing, of associating their ideas; their volition, their memory have fled, and all the functions of organic life are more or less disturbed. Rousseau never proved more clearly that his own intellectual faculties were occasionally impaired, than when he stated "that the state of reflection is unnatural, and that the man who meditates is a depraved animal." Insanity may be divided into four species: 1st, _Monomania_, and _melancholy_, in which the delirium is confined to one or few objects. 2nd, _Mania_, where the delirium embraces a variety of impressions, and is accompanied with violence. 3rd, _Dementia_, or insanity in the full acceptation of the word, where the senses are totally bewildered, and the faculty of thinking destroyed. 4th, _Imbecility_ or _idiotcy_, where, from imperfect organisation, ratiocination cannot be correct.