_Illusions._--When illusions are present, the mind fails to perceive correctly what the eye sees, or the ear hears, or the impressions that are brought to the brain from any of the organs of sense. For instance, a person looks at a row of trees, and they appear to him to be a row of soldiers; or the whistle of a locomotive may be so changed as to seem to be the voice of God; or the odor of a rose, burning sulphur; food may taste like poison, or the hand of a friend feel like a piece of ice or a red-hot iron, and is so believed to be. These are deceptions of the senses. In insanity, the truth and existence of delusions, hallucinations, and illusions are fully believed in, and the patient cannot be argued out of the belief, however absurd or unreal it may be. _Incoherence of Speech._--When a person is incoherent, he rambles in talk; there is little connection between different sentences, or the sentence itself is meaningless, being a mere jumble of words; sometimes ideas come too rapidly into the mind, and some new subject is begun and talked about before the first is finished; sometimes the mind is slow, and memory forgets what is being talked about. _General States of Insanity._--There are a few general mental states in insanity, one of which being present gives the character and name to the disease. These are: _a._ A state of exaltation of mind, or mania. _b._ A state of depression of mind, or melancholia. _c._ A state of enfeeblement of mind, or dementia. But one of these first two states of feeling can be present at the same time, for a person cannot at any one moment be both exalted and depressed, though he have mania to day, and afterward be so changed in his feeling as to have melancholia to-morrow, or next week, or next month. In a general way all disease is divided into acute and chronic forms. An acute disease is one of recent origin, and from which recovery is to be hoped for; a chronic disease is prolonged and does not tend to recovery; an acute disease may become chronic. Mania and melancholia are at first considered acute and curable, but, if recovery does not take place, they pass into either chronic mania or chronic melancholia, or, if the mind is much enfeebled, into a condition of dementia. _Mania._--In mania the mind is generally very active, though lacking in control, and is irregular and illogical in its action; the patient talks rapidly, and upon many subjects, and is often incoherent, or he laughs, sings, dances, or cries, perhaps in turn; he is often irritable and unreasonable, and perhaps threatening, and becomes more violent if interfered with. Accompanying this mental excitement there is frequently persistent loss of sleep, constant restlessness, and great bodily activity, and indifference to or refusal of food. Sometimes the brain excitement is so great that all self-control is lost, and the patient becomes a raving maniac.