Now we have only to suppose a person with a nervous system so constituted that these conditions, which I have described as temporarily occurring with many persons from exciting causes, are permanent, though in a latent state, and we have that peculiar organization which we term _The Insane Diathesis_. That is, we have a nervous system so sensitively constituted, and illy adjusted with its surroundings, that when brought in contact with unusually exciting influences, there may occur deranged instead of natural mental action, and it becomes more or less continuous instead of evanescent. The mind passes from the control of the will, and wanders hither and thither, or persistently holds on in one channel of thought. Its action may become spasmodic and irregular in all degrees from slight aberrations, or excitement, up to incoherence and mental spasm; or from slight degrees of depression, down to almost inactivity and dementia: in short, such abnormal conditions of mental activity as constitute insanity. The husband hates his wife, and the wife her husband; the parent his child, and the child the parent. We have the person, whose brain is so perverted in its action that he feels no pleasure and experiences no satisfaction in life, but hates it, and longs to throw off its burdens and cares, and leaves no effort untried to accomplish it; while another is so filled with joyous emotion, his brain is so excited in functional activity, that he can neither eat nor sleep, but ideas flow forth in one constant stream of words--words; bright visions appear on every side, and his life is worth a thousand worlds. Or, we may have any other of the ten thousand perverted mental activities which attend the "mind diseased." "And he * * * (a short tale to make) Fell into a sadness; then into a fast; Thence into a watch; thence into a weakness; Thence into a lightness; and by this declination Into a madness, whereon he now raves And we all mourn for." In the above view, there does not appear to be any well-defined, sharply bounded line between what is termed normal and abnormal mental activity in its primary stage. The one insensibly merges into the other, while both depend upon the physiological condition of the brain for the time being. When that portion of it which is immediately concerned in thought is in what is termed a healthy state, that is, a condition in which its involuntary functions are normally performed and under the control of the will, then we have healthy mind; and, _vice versa_, when it varies from this condition, either from the effect of influences which have been inherited or acquired, then we have for the time, abnormal mind. Thousands are born into the world with brains so constituted as to become easily deranged by external influences and experiences, and thousands more attain to such conditions of the brain, from the frictions of life, and abuse of its enjoyments and requirements.