THE INSANE TEMPERAMENT (Insane Diathesis, Neuro-psychopathische Constitution) is an exaggeration of the nervous temperament. It is closely allied to insanity and the neuroses, and at the critical periods of life is very apt to develop into one of them. It is congenital or due to early interference with the normal development of the brain by injury or disease. It shows itself in childhood and infancy by irregular or disturbed sleep, irritability, apprehension, strange ideas, great sensitiveness to external impressions, high temperature, delirium, or convulsions from slight causes, disagreeable dreams and visions, romancing, intense feeling, periodic headache, muscular twitchings, capricious appetite, and great intolerance of stimulants and narcotics. At puberty developmental anomalies are often observed in girls, and not seldom perverted sexual instincts in both sexes. During adolescence there are often excessive shyness or bravado, always introspection and self-consciousness, and sometimes abeyance or absence of the sexual instinct, which, however, {141} is frequently of extraordinary intensity. The imitative and imaginative faculties may be quick. The affections and emotions are strong. Vehement dislikes are formed, and intense personal attachments result in extraordinary friendships, which not seldom swing suddenly around to bitter enmity or indifference. The natural home associations and feelings easily become disturbed or perverted. The passions are unduly a force in the character, which is commonly said to lack will-power. The individual's higher brain-centres are inhibited, and he dashes about like a ship without a rudder, fairly well if the winds are fair and the seas calm, but dependent upon the elements for the character and time of the final wreck. Invention, poetry, music, artistic taste, philanthropy, intensity, and originality are sometimes of a high order among these persons, but desultory, half-finished work and shiftlessness are much more common. With many of them concentrated, sustained effort is impossible, and attempts to keep them to it result disastrously. Their common sense, perception of the relations of life, executive or business faculty, and judgment are seldom well developed. The memory is now and then phenomenal. In later life there is a ready reaction to external circumstances, even to the weather, by which the individual is usually a little exhilarated or somewhat depressed. All sorts of vaso-motor disturbances are common and create distressing symptoms. Such people are said to be on the border-line between sanity and insanity. They are apt to be self-conscious, egoistic, suspicious, and morbidly conscientious; they easily become victims of insomnia, neurasthenic, hypochondriacal, neurotic, hysterical, or insane, and they offend against the proprieties of life or commit crimes with less cause or provocation than other persons. At the same time that many of