CLASSES OF DISEASE FROM MORAL AGENCIES.
Diseases developed through the nervous system are those most distinctly brought out through the agency of moral causes. The effect of shock from mental disturbance is one amongst the most marked of the diseased conditions so induced. A mental shock from bad news suddenly communicated, from intense grief, from intense disappointment, and in very sensitive natures from some sight or sound, and specially from sound, is all-sufficient to create an effect in the nervous system so similar to that which is produced by common physical accidents as to be indistinguishable by effect. Thus in ordinary conversation we are wont to speak of persons being stunned by the news they have heard; or of persons being rendered bloodless and faint on receipt of over whelming intelligence; or, of persons being palsied by the effect of some painful or alarming impression that has been made upon them through the mind.
Thus we have at once three physical phenomena of disease through the nervous system presented to observation as possibly due to mental agency, and these diseases of major import; con cussion, syncope, palsy. The list does not end here, for it some times happens that diseases of a chronic kind are indirectly pro duced from a mental blow, of which diseases diabetes sometimes offers a striking example.
Again, the subtle train of physical diseases through mental agencies may be induced, without any shock, through mere mat ter of imitation, the affected person, predisposed, perchance, to the affection afterwards developed, showing the first signs of the malady on being simply in personal contact with some one suf fering from the affection. In these cases the form of disease indicated is commonly a muscular excitement brought out by the nervous disturbance, and is for a long time continuous if not permanent.
Once more, in certain unhealthy conditions of the body, where the arterial tone is feeble and the balance between the heart and its recoil is uncertain, and where, also, accompanying this state or leading up to it the nervous ether is deranged or modified, very slight external physical causes, causes which are not felt by healthy persons, are sufficient to set up in susceptible persons one or other of a long series of symptoms, which may simulate any of the true physical diseases.
In these instances the causes at work may act through any of the senses—the smell, the taste, the touch, the seeing, the hear ing. We say, there is exalted sensibility in the persons affected. The definition is quite correct. We say, for want of a better term, that the persons affected are hysterical or hysterically dis posed. It would be more correct to say that they are for the time living tinder a different constitution or state of body from that which is natural. They are, in a word, in a special state of ner vous tension, so that every vibration in themselves, so that every vibration outside themselves, whether arising from motion of parts of the body, or from mental fluctuations, or from variations in external temperature, or other external causes, may be sufficient to develop temporary phenomena of disease, exhibited through the nervous and muscular systems.
It not unfrequently happens that in the persons of this hys terical nature, the causes which lead to concussion, syncope, and paralysis come into play with unusual effect; so that the hysteri cal are specially predisposed to be stunned, to be rendered faint, to be paralyzed, by influences which do not affect their stronger and less susceptible companions. They are, too, more easily af fected by the observation of peculiar or distressing actions, and are thereby rendered more liable to diseases induced by imitation.