The picture of the neurasthenic, or hypochondriac, who has educated himself, as Plato says, into disease, is an interesting parallel to modern conditions in this matter.
Nowhere more than in this matter of knowledge of disease, can weight be attached to Pope's dictum that a little knowledge is a dangerous thing, and that one must drink deep or touch not the Pierian Spring of medical information. The teaching of pathology under the guise of physiology, now so common in our schools, is likely to do more harm than good. Various pathological conditions, such as those produced by alcohol and tobacco, have been emphasized to such an extent as to produce unfavorable suggestions in the pupils' minds with regard to the untoward events that may happen in their insides, and the serious lasting pathological changes that may occur, though all unconsciously, to the sufferer as the result of indiscretions. The study of the morbid changes produced in the mucous membranes of the digestive tract by the use of stimulants, impresses ideas on the mind that are readily transferred to other abuses in eating or drinking. The rather vivid pictures and descriptions of the pathological conditions that may develop, become a portion of the acquired consciousness as to internal conditions, and this consciousness acts as an unfavorable suggestive factor whenever there are any digestive symptoms.
Bacteriphobia.—The development of bacteriology has had a similar effect, especially because periodicals and newspapers like to take up only the sensational side of biological discoveries. Most physicians who have had anything to do with nervous diseases have seen cases of misophobia, the fear of dirt, which in our day has taken on the special character of fear of microbes. Those who are sensitive to the possibility of contamination learn of the almost sacrificial precautions that surgeons take to avoid wound infection, and conclude that practically everything they handle must fairly reek with microbes. They hesitate about touching the door knob or latch, and invent all sorts of excuses to wait for a moment outside the door in order to have someone else open it. Especially are they timorous about touching the door knobs of a physician's residence, or the chairs in his waiting room, or even to shake hands with him. Hospital walls and doors become an abomination to them. These cases emphasize how much of unfavorable suggestion there has been in the present spread of popular knowledge with regard to microbes.
A writer on popular science once said that every time we spread a piece of bread of the size of the hand with butter, we scatter over its surface as many microbes as there are inhabitants in the United States. The expression has gone the rounds, producing its effect on sensitive people, occasionally causing even a disgust for so important an article of diet as butter, more often giving rise to an extreme sensitiveness with regard to any special savor that butter may have, and it may have many according to the prevailing food of the cow. There has been much emphasis laid on the potentialities for harm of the microbes, and very little on the important part which they play in the production of many forms of food materials. Most people know and dread the fact that microbes produce disease. Very few seem to realize that while we know many thousands of different kinds of microbes, scarcely more than a score of them are known to be seriously pathogenic, while all the others are either indifferent or, as we know of very many, are actually benefactors of mankind.
People have heard much of the flora of the digestive tract, until they have come to think with anxiety of the almost infinite number and multitudinous variety of the minute plant life that finds a habitat in the human intestine. Most people think that all of these are, in tendency at least, harmful, and are only kept from being positively dangerous by the overwhelming vital activity of the mucous membrane and the secretions which keep them from exerting their malign activity. Very few appreciate the fact that the intestinal flora, far from being a disturbing factor, are often an aid to digestion, and that the equilibrium established among them favors many biological and chemical processes which help in the preparation of food and in the breaking up of waste products that might be dangerous if reabsorbed during their stay in the intestinal tract. Microbes we have always with us and always will have, and men have lived to round old age, not only in spite of them, but very probably partially because of them. They are part of that beneficent mystery of nature of which as yet, in spite of scientific progress, we know comparatively little.
Opposing Favorable Suggestion ,—A recent striking change of sentiment with regard to one form of food material furnishes a good example of how little we know about the real effect of bacterial life within the digestive tract. There was a time, not so long since, when sour milk was supposed to be especially harmful, or at least only likely to do good to those of particularly strong digestive vitality. Metchnikoff's work on the influence of sour milk on the digestive tract, however, has brought a complete reversal of opinion in this matter. Now most physicians are convinced that the bacillus of sour milk, acts in the intestinal tract to inhibit the reproduction and growth of other, and possibly more disturbing, bacterial agents. Sour milk is looked upon as one of the things that, by neutralizing certain unfortunate bacterial processes in the digestive tract, lead to longevity. There seems no doubt at all, that those who consume a great deal of it, live longer lives than the average, and many old men have taken to its use with a consequent amelioration of digestive annoyances.
The popularization of bacteriology, then, has been one of those moments of unfavorable suggestion that have affected a large number of people. Such influences do not mean much for people of phlegmatic temperament. For others, however, they have a weighty significance and make every symptom, or more properly every sensation, that is at all unusual in the digestive tract, seem of ominous import. Certain sensations inevitably accompany digestion. The peristaltic movements are usually said to be unfelt, but even a slight exaggeration brings them into the sphere of sensation. Where attention is given to the abdominal region and its contents, feelings that ordinarily are not noticed at all come to be perceived. With the unfavorable suggestion derived from the unfortunate diffusion of a superficial knowledge of pathology and of bacteriology instead of hygiene and the science of beneficent microbiology, these feelings produce a bad effect upon the individual.
Familiar Examples of Unfavorable Suggestion.—There are many familiar examples of the discomfort that may be produced by the mental persuasion that something will disagree with us, or that certain feelings have a significance quite beyond that which ought to be attributed to them. Everyone knows how qualmy may be the feeling produced by being told that something eaten with a relish contained some unusual material, or was cooked under unclean conditions. Food that agrees quite well with people, so long as they do not know too much about it, often fails to be beneficial after they see how it has been prepared. It is often said that people would not relish the food placed before them if they were aware how lacking in cleanliness was the place of its preparation, and how negligent those who had charge of it. Occasionally a peep at the kitchen of a boarding house effectually takes away appetite, or disturbs the equanimity with which food must be taken, if there is to be that undisturbed digestion which makes for healthy nutrition.
It is, indeed, with regard to digestion that the influence of the mind on the body, favorable as well as unfavorable is, perhaps, most effectively exercised. Unfortunately the unfavorable influence is even more pronounced than its opposite. Some people are much more sensitive than others in this respect, and even the thought of certain defects in the preparation of their food seriously disturbs them. Everyone has had the experience of seeing sensitive persons leave the table because some one insisted on telling a nauseating tale. Anyone who has seen the effect of talking of blood sausage or fried brains with black butter sauce at a table on shipboard, when some practical joker was exercising his supposed wit, knows how much the imagination can disturb, not only appetite but digestion. The attitude of mind means much, and especially are such unfavorable suggestions likely to produce serious effects in inhibiting digestion.
Suggestion and Seasickness .—Seasickness illustrates the place of unfavorable suggestion in digestion. The nausea,