progressively to the number ten, and knew the force and value of the separate units, he would be fully competent to the management of property; if he could comprehend that twice two composed four, he could find no difficulty in understanding that twice, or twain ten, constituted twenty. This _numeration_ also presumes he comprehended that so many taken from ten, or subtracted, which is the converse, would leave so many as the remainder. Without such capacity, no man, in my own opinion, could understand the nature of property, which is represented by numbers of pounds, shillings, and pence. The same imbecility of mind is often produced in adults, and in those of advanced age, by paralytic or epileptic attacks, and from various affections of the brain, and requires the same accurate investigation to determine on the competency of such persons to be entrusted with the management of themselves and affairs.” In cases of _Amentia acquisita_, our prognosis must be directed by different circumstances: the faculties of a person may only be in abeyance, and may revert to a state of sanity, either spontaneously, or from judicious treatment, or they may be only partially affected.[522] It however deserves notice that, in extent of mortality, the most fatal of all the states of mental disorder is _Amentia acquisita_; it has been computed that in the French hospitals a full moiety of the fatuous die; at the same time, it appears from the reports of lunatic asylums, that this disorder is sometimes cured. Idiots are, in general, harmless; their deportment being characterised by a timidity that guards them from any mischievous attempts, either upon themselves or upon other persons; to this general rule, however, exceptions not unfrequently occur; as, for instance, in the unfortunate case of the idiot in Cornwall who strangled, and afterwards burnt the body of, an old woman who had for some years superintended his person. In some cases of accidental fatuity, a considerable disposition to obesity manifests itself, and the subject becomes lethargic.