ACQUIRED DISEASE FROM MORAL AGENCIES.
The class of affections which admit of being considered as arising purely from moral agencies are either directly imitative in respect to origin, or hereditary, or a combination of imitation and hereditary proclivity. Probably in a great majority of in stances the hereditary proclivity is the basis, while the imitative action, by which the phenomena of disease are rendered mani fest and often permanent, is only called forth because the ten dency or aptitude towards the imitation is strongly developed. Imitation of phenomena of disease is not indeed materially dif ferent, except in results, from that power of imitation which makes some persons excel in the various arts and exercises of skill in which it is commonly said they are born to excel.
To a certain extent every person is imitative, and many of the commonest acts of life are the results of imitation. No two per sons live together for many years without assuming some charac teristics common to both, the weaker acquiring, as a rule, the characteristics of the stronger. Features themselves are modified by imitation, and so it is a matter of every-day observation that married couples become so much alike that they might be mis taken for brother and sister, in which observation we detect how intimately the hereditary and the acquired faculties of our nature blend the one with the other.
It is not surprising then that persons of feeble, nervous organ ization should come, incidentally, under the spell of imitation in relation to disease, and that we should have presented to us in nature, amongst the representatives of human kind, a series of diseases depending for their development on moral agencies.
Esquirol, who seems to have been amongst the first to recog nize clearly and to define these diseased conditions or diseases, treats of them as diseases of sympathy, while the learned Prosper Despine of Marseilles of our day, treats of them as due to moral contagion.
In many points of view the hypothesis of contagion, taking the word in its general sense, is not only correct but exceedingly expressive. The diseases induced by moral contagion are analo gous to some extent to those which are traceable to physical con tagion. Sometimes they take a spreading or epidemic character, after the manner of the ordinary spreading or contagious affec tions more commonly known as catching affections or pestilences, in which case they may widen into great epidemic outbreaks. Sometimes they assume what is called a sporadic form, that is to say, they are confined to a limited number of persons living in a limited district. Sometimes they take what is called the idiopathic form, that is to say, they appear only in particular individuals.
When the diseases dependent on moral influences have as sumed their widest extension, it has been observed that, like the commoner epidemics, they have exhibited their periods of origin, intensity, and decline. The analogies go further. A common con tagious disease is often traceable to an imported case, or to what may have been designated, a case of spontaneous origin. In the moral epidemics the same modes of development are discoverable. During a common epidemic one prevailing disease may seem dominant. The like has been observed during moral epidemics. In common epidemics all persons are not equally susceptible to the influence of the contagion; some are extremely susceptible, others are insusceptible. The same obtains in relation to the diseases of moral origin, whether they are of epidemic, sporadic, or idiopathic character.
Again, physical contagious diseases, such diseases as small pox, scarlet fever, and the like, present their greatest activities at particular seasons of the year, and that with such regularity as to enable the periods of intensity of these diseases to be marked out and classified. Something similar has been observed in respect to the diseases of moral origin. Thus the Rev. W. Archibald, in a description of a peculiar imitative convulsive disease of moral type, which appeared in the Shetland Islands, showed that the affection was only presented during the season of summer.
It occasionally happens during times when an ordinary con tagious disease is present that the disease, say it be cholera, appears to excite a similar form of disease, simply by the moral influence which it exercises. Under these circumstances physi cians themselves may be placed in the greatest difficulty in deter mining whether a suffering person is affected by the actual malady, or only by a moral or simulated attack; the chief point of diagnosis being that the simulated disease is usually of shorter duration, and rarely fatal. Here the mental and physical con ditions blend.
The analogy between the physical and the moral diseases is further supported by the circumstances that a moral epidemic sometimes succeeds, and, as it were, supersedes a physical. This fact is so marked that it forms, as we shall see, a conspicuous feature in the histories of some great physical and moral epi demics. Lastly, both classes of disease, moral and physical, are most readily suppressed by the plan of separating the diseased from the healthy.
The analogies above presented are sufficiently striking, but it is fair to indicate that there are also differences between the two classes of phenomena. In the first place, moral contagion appears generally to be easily detectable, the time when the imitation took place and all else that relates to the mode of transmission being recognized or recognizable. Physical contagion, on the other hand, though it may be essentially physical and material in its nature, may neither be detectable nor definable by present facilities of observation. In the second place, the diseases of moral origin are not independent in character, they are truly simulated, or simulative affections assuming the form of some other well-known disease which is, or may be considered, of purely physical character. This fact will be brought out by the history of certain of the moral or imitative diseases which have to be described.