is only to be noted in extreme cases. Steffens says, for example[1]—“We are forced to the conclusion that in essence hysteria and epilepsy are not fundamentally different, but that the cause of the disease is the same but is manifest in a diverse form, in different intensity and permanence.”
The demarcation of hysteria and certain borderline cases of epilepsy, from congenital and acquired psychopathic mental deficiency, likewise presents the greatest difficulties. The symptoms of one or other disease everywhere invade the neighbouring realm, so violence is done to the facts when they are split off and considered as belonging to one or other realm. The demarcation of psychopathic mental deficiency from the normal is an absolutely impossible task, the difference is everywhere only “more or less.” The classification in the region of mental deficiency itself is confronted by the same difficulty. At the most, certain classes can be separated off which crystallise round some well-marked nucleus through having peculiarly typical features. Turning away from the two large groups of intellectual and emotional deficiency, there remain those deficiencies coloured pre-eminently by hysteria or epilepsy (epileptoid) or neurasthenia, which are not notably deficiency of the intellect or of feeling. It is pre-eminently in this region, insusceptible of any absolute classification, that the above-named conditions play their part. As is well known, they can appear as part manifestations of a typical epilepsy or hysteria, or can exist separately in the realm of psychopathic mental deficiency, where their qualifications of epileptic or hysterical are often due to the non-essential accessory features. It is thus the rule to count somnambulism among hysterical diseases, because it is occasionally a phenomenon of severe hysteria, or because mild so-called hysterical symptoms may accompany it. Binet says: “Il n’y a pas une somnambulisme, état nerveux toujours identique à lui-même, il y a des somnambulismes.” As one of the manifestations of a severe hysteria, somnambulism is not an unknown phenomenon, but as a pathological entity, as a disease sui generis, it must
- ↑ Arch. f. Psych., XXXIII. p. 928.
