Those who have not opportunities of observing how all-powerful is the effect of the mind upon the body, and especially perhaps upon the process of digestion, may find it hard to believe that these distressing symptoms and profound changes in the aspect and nutrition of the patients were due entirely to mental causes and were symptoms in accord with the attempted suicide or the theft of the money.  In nervous little children we shall not often find such complex actions as suicide or theft, although they do occur, but combined with other evidence of nervousness we shall meet commonly enough with a persistent setting aside of appetite and refusal of food and with continuous and habitual vomiting, from nervous causes.

The experiments of Pawlow and others have explained the dependence of digestion upon mental states.  They show that even before the food is taken into the mouth, while the meal is still in prospect, there has been instituted a series of changes in the wall of the stomach, which gives rise to the so-called psychic secretion of gastric juice.  These changes are preceded by the sensation of appetite, which is evoked not by the presence of food in the stomach—­for the food has not yet been swallowed—­but by the anticipation of it, by the sight and smell of food, as well as by more complex suggestions, such as the time of day, the habitual hour, the approach of home, and so forth.

Emotional states of all sorts—­grief, anger, anxiety, or excitement—­put a stop to the process or interfere with its action, so that the sense of appetite is absent, and the taking of food is apt to be followed by discomfort or pain or vomiting.  No doubt good digestion leads to a placid mind, but it is equally true that a placid mind is necessary for good digestion.  Therefore we civilised people, living lives of mental stress and strain, try to increase the suggestive force of our surroundings and to provoke appetite by all devices calculated to stimulate the aesthetic sense.  The dinner hour is fixed at a time when all work and, let us hope, all worry is at an end for the day.  The dinner-table is made as pretty as possible, with flowers and sparkling glass.  We are wise to dress for dinner, that with our working clothes we may put off our working thoughts.

In the treatment of adult dyspepsia we seldom succeed unless we can place the mind at rest.  We may advise a visit to the dentist and a set of false teeth, or we may administer a variety of stomach tonics and sedatives, but if the mind remains filled with nameless fears and anxieties we shall not succeed.