_(a) Hysteria._—This is well illustrated in the history of epidemic hysteria. It may occasionally be seen among ourselves in a hospital ward or at a camp-meeting; but such outbreaks are sporadic. They belong in the ethnic temperament of many tribes of the Malayan and native American races. The Jesuit fathers described in vivid colours such outbreaks among the Hurons of Canada, attacking whole villages and frequently leading to their destruction. Father de Quen was quite right when he wrote: “The old saying alleges that every man has a grain of madness in his composition; but this is a tribe where each has half an ounce.” He correctly regarded them as in a permanently pathological state. Quite similar recitals are preserved of such outbreaks among the Guaranis of Paraguay, and other primitive stocks, notably the Malay peoples. From the accounts of travellers it would seem, contrary to what we might suppose, that such excessive nervous sensibility is peculiarly present in extreme northern latitudes, while tropical tribes are much more liable to conditions of depression. Castren, who lived long among the northern Sibiric tribes, dwells with astonishment on their nervous sensitiveness. A sudden blow on the outside of the skin yurt will throw its occupants into spasms. Among these “neuroses of excitement” which at times seize upon the souls of communities, none is more inexplicable, and none more fraught with consequences to world-history than the goading restlessness which has driven single tribes or groups of tribes into aimless roving. This _Wanderlust_ arises as an emotional epidemic, not by a process of reasoning. It drives communities from fixed seats and comfortable homes, transforming them into migratory and warring hordes. _(b) Exaltation._—Under the heading of exaltation of nervous impulse the alienist includes a morbid devotion to sexual thoughts and acts (erotomania); to vanity, ambition, and self-magnification; and those states of megalomania where the patient is subject to delusions of greatness, _idées de grandeur_. To all of these we may easily find parallels in ethnic life. They have all their analogies in tribal or national history, with consequences as disastrous as they disclose in the individual. No more positive examples of erotic mania could be found in an asylum than those presented by the whole of some Polynesian tribes. The life of both sexes was devoted chiefly to the pleasures of the genital nerves. Societies were formed where such practices were developed into arts; children before maturity were initiated into them; and no mode of excitement, unnatural though it might be, was omitted or shunned.