The author considers that pain and its analogues, malaise, discomfort, ill-being, etc., whether of functional or organic origin, being forms of sensation, are essentially mental phenomena arising in the brain, and can be removed by psychotherapy. That the mind can act upon the body and influence every function is a well-established fact. It is possible, too, that certain organic changes, vascular disease, heart disease, etc., may be traced to certain mental processes—anxiety—causing, excessive secretion by the adrenals. In every case of illness some of the symptoms are due to suggestion either from within or from without. This was seen in many of the “slow recoveries” in the war due to auto-suggestion. In organic disease psychotherapy cannot effect a cure, but in every case it can assist and give relief to suffering, e. g. pain in cancer. In earlier days suggestion was employed unconsciously in the use of charms, amulets, religious relics, etc., in later days in mind-cures and Christian Science. The relief of symptoms shows that faith alone is a potent curative agent, and that the majority of the ordinary symptoms are mental in nature and removable. The methods employed in psychotherapy are suggestion under hypnosis, suggestion in the waking state, persuasion and re-education, and psycho-analysis. In “superficial” cases immediate results often follow suggestion, but in the more chronic cases the removal of a symptom by suggestion is often followed by relapses, a new symptom taking the place of the rejected one, as the underlying condition of morbid suggestibility has not been removed. To overcome this condition Dubois introduced the method of persuasion. He thinks that an appeal should be made to the intellect by talks with the patient on the subject of his nervous symptoms. Persuasion is to some extent a form of suggestion, as in all degrees of belief feeling as well as the intellect is involved. Upon re-education largely rests the completeness of the cure; the connection between the mental antecedents and the symptoms are explained to the patient; when these are understood and acted upon his mal-adaptation ceases. Freud has shown that the patient may be most profoundly influenced by feelings and ideas of which he is quite unconscious. No persuasion avails until the unconscious motive of his mental or nervous symptoms has been uncovered. The process by which this can be done is known as psycho-analysis. Three methods of probing the unconscious mind are mentioned—the word-association test, the free association of ideas, and the analysis of dreams. Psycho-analysis has its limitations. It is not usually successful in curing persons above middle age; even when successful the treatment may take months. Robertson thinks that in many cases it is unnecessary. No successful physician who has not given attention to this subject has the faintest idea of the extent to which he employs psychotherapy unconsciously. Every practitioner and student of medicine must be taught the part the mind plays in the chief symptoms of disease, and he must consciously use psychotherapy in the treatment of these. His success will depend on the depth of his convictions.