INSANITY1, med. jur. A continued impetuositv of thought, which, for the time being, totally unfitsga man for judging and acting2 in relation to the matter in question, with the composure requisite3 for the maintenance of the social relations of life. Various other definitions of this state have been given, but perhaps the subject is not susceptible4 of any satisfactory definition, which shall, with, precision, include all cases of insanity, and exclude all others. Ray, Med. Jur. 24, p. 50.
2. It may be considered in a threefold point of view: 1. A chronic6 disease, manifested by deviations7 from the healthy and natural state of the mind, such deviations consisting in a morbid8 perversion9 of the feelings, affections and habits. 2. Disturbances10 of the intellectual faculties11, under the influence of which the understanding becomes susceptible of hallucinations or erroneous. impressions of a particular kind. 3. A state of mental incoherence or constant hurry and confusion of thought. Cyclo. Practical Medicine, h. t.; Brewster's Encyclopaedia12, h. t.; Observations on the Deranged13 Manifestations14 of the Mind, or Insanity, 71, 72; Merl. R«pert. mots Demenoe, Folie, Imbecilite; 6 Watts15 & Serg. 451.
3. The diseases included under the name of insanity have been arranged under two divisions, founded on two very different conditions of the brain. Ray, Med. Jur. ch. 1, 33.
4. - 1. The want of, or a defective16 development of the faculties. 1st. Idiocy17, resulting from, 1. Congenital defect. 2. An obstacle to the development of the faculties, supervening in infancy18. 2d. Imbecility, resulting from, 1. Congenital defects. 2. An obstacle to the development of the faculties, supervening in infancy.
5. - 2. The lesion of the faculties subsequent to their development. In this division may be classed, 1st. Mania19, which is, 1. Intellectual, and is general or partial. 2. Affective and is general or, partial. 2d. Dementia, which is, 1. Consecutive20 to mania, or injuries of the brain. 2. Senile, or peculiar21 to old age.
6. - There is also a disease which has acquired the name of Moral insanity. (q. v.)
7. Insanity is an excuse for the commission of acts which in others would be crimes, because the insane man has no intention; it deprives a man also from entering into any valid22 contract. Vide Lunacy; Non compos mentis, and Stock on the Law of Non Compotes Mentis; 1 Hagg. Cons5. R. 417; 3 Addams, R. 90, 91, 180, 181; 3 Hagg. Eccl. R. 545, 598, 600; 2 Greenl. Ev. 369, 374; Bouv. Inst. Index, h. t.
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