I refer not merely to the so-called nervous diseases, the neuroses and psychoses, the myriad forms of nervousness without recognizable basis in organic disease, but also to the mental complications and results of serious organic diseases such as tuberculosis, arteriosclerosis, and surgical injuries. The classical studies of Charcot, Pierre Janet, and others have made clear to the whole world the existence of a body of diseases in which the mental functions are obviously deranged while still the patient is not insane in any legal sense, and does not show on physical examination any evidence of gross organic disease. Neurasthenia, psychasthenia, hysteria, are among the more common types marked out by the studies of great psychologists and clinicians. Little or nothing has been added by the studies of German, American, and English physicians to our knowledge of these diseases. But throughout the history and development of France's leadership in the study of these diseases, one cannot help noticing that interest is concentrated largely upon diagnosis; comparatively little attention is paid to treatment. The great leaders have not been extensively followed. Their suggestions have not been carried out on a large scale nor followed sufficiently into the field of practical therapeutics. Especially is this true in the field of _visceral neuroses_ or nervous symptoms referred by the patient to one or another organ--the stomach, the pelvic organs, the bowels--in which nevertheless no evidence of disease can be found. In these diseases English, French, and American physicians alike persist for the most part in humoring and soothing the patient by the administration of remedies known to have no real influence upon disease and designed chiefly to make the patient feel that something is being done for him. This is superficial treatment. It makes no attempt to attack the determining causes of the disease. Whether or not there are any psychogenic diseases, whether or not purely psychical events can be proved to produce the group of symptoms known as neurasthenia, psychasthenia, or hysteria, or whether there are physical causes contributing to produce the symptoms, this at any rate may be said with confidence: that if we are to root out the patient's trouble, if we are to bring about anything approaching a radical cure, we must attack the mental symptoms directly and upon their own grounds, that is, by mental means, chiefly by reëducation. _The mental element in these diseases is at any rate the most vulnerable point of attack._ It is here that we can most profitably exert therapeutic pressure.