Psychotherapy is the practice of treating the sick by influencing the mental life. It stands at the side of physicotherapy, which attempts to cure the sick by influencing the body, perhaps with drugs and medicines, or with electricity or baths or diet.

Psychotherapy is sharply to be separated from psychiatry, the treatment of mental diseases. Of course to a certain degree, mental illness too, is open to mental treatment; but certainly many diseases of the mind lie entirely beyond the reach of psychotherapy, and on the other hand psychotherapy may be applied also to diseases which are not mental at all. That which binds all psychotherapeutic efforts together into unity is the method of treatment. The psychotherapist must always somehow set levers of the mind in motion and work through them towards the removal of the sufferer's ailment; but the disturbances to be treated may show the greatest possible variety and may belong to mind or body.

Treatment of diseases by influence on the mind is as old as human history, but it has attained at various times very different degrees of importance. There is no lack of evidence that we have entered into a period in which an especial emphasis will be laid on the too long neglected psychical factor. This new movement is probably only in its beginning and the loudness with which it presents itself to-day is one of the many indications of its immaturity. Whether it will be a blessing or a danger, whether it will really lead forward in a lasting way, or whether it will soon demand a reaction, will probably depend in the first place on the soberness and thoroughness of the discussion. If the movement is carried on under the control of science, it may yield lasting results. If it keeps the features of dilettanteism and prefers association with the antiscientific tendencies, it is pre-destined to have a spasmodic character and ultimately to be harmful.

The chaotic character of psychotherapy in this first decade of the twentieth century can be easily understood. It results from the fact that in our period one great wave of civilization is sinking and a new wave rising, while the one has not entirely disappeared and the other is still far from its height. The history of civilization has shown at all times a wavelike alternation between realism and idealism, that is, between an interest in that which is, and an interest in that which ought to be. In the realistic periods, the study of facts, especially of the facts of nature, is prevalent; in idealistic periods, history and literature appeal to the world. In realistic periods, technique enjoys its triumphs; in idealistic periods, art and religion prevail. Such a realistic movement lies behind us. It began with the incomparable development of physics, chemistry, and biology, in the middle of the last century, and it brought with it the achievements of modern engineering and medicine. We are still fully under the influence of this gigantic movement and its real achievements will never leave us; and yet this realistic wave is ebbing to-day and a new period of idealism is rising. If the signs are not deceitful, this new movement may reach its historical climax a few decades hence, when new leaders may give to the idealistic view of the world the same classical expression which Darwin and others gave to the receding naturalistic age. The signs are clear indeed that the days of idealistic philosophy and of art, and of religion, are approaching; that the world is tired of merely connecting facts without asking what their ultimate meaning is. The world dimly feels again that technical civilization alone cannot make life more worth living. The aim of the last generation was to explain the world; the aim of the next generation will be to interpret the world; the one was seeking laws, the other will seek ideals.

Psychotherapy stands in the service of both; it is the last word of the passing naturalistic movement, and yet in another way it tries to be the first word of the coming idealistic movement; and because it is under the influence of both, it speaks sometimes the language of the one, and sometimes the language of the other. That brings about a confusion and a disorder which must be detrimental. To transform this vagueness into clear, distinct relations is the immediate duty of science.Indeed it may be said that psychotherapy is the last word of a naturalistic age, because psychotherapy finds its real stronghold in a systematic study of the mental laws, and such study of mental laws, psychology, must indeed be the ultimate outcome of a naturalistic view of the world. Realism begins with the analysis of lifeless nature, begins with the study of the stars and the stones, of masses and of atoms. At a higher level, it turns then to the living organism, studies plants and animals and even brings the human organism entirely under the point of view of natural law. When science has thus mastered the whole physical universe, it finally brings even the mental life of man under the naturalistic point of view, treats his inner experiences like any outer objects, tears them in pieces, analyzes them, and studies them as functions of the nervous system. A scientific psychology is thus reached which is the climax of realism, because it means that even the ideas and emotions and volitions of man are treated as natural phenomena, that their causes are sought and that their effects are determined, that their laws are found out. To apply this realistic knowledge of the mind in the interest of therapy is merely to use it in the same way in which the engineer uses his knowledge of physics, when he wants to harness outer nature. As that is possible only when theoretical science has reached a certain height of development, it can indeed be said that practical psychotherapy on a scientific basis can be considered almost as the ultimate point of a realistic movement; it cannot set in until psychology has reached high development, and psychology cannot set in unless biology has preceded it.

There is no doubt that we are still far from this last phase of the realistic period. The practical application of scientific psychology is still a new problem. Experimental psychology began about twenty-five years ago; at that time there existed one psychological laboratory. To-day there is no university in the world which does not have a psychological workshop. But laboratories for applied psychology are only arising in these present days, and the systematic application of scientific psychology to education and law and industry and social life and medicine is almost at its beginning. While the height of the last realistic wave was in the period of the sixties, seventies, and eighties, of the last century, its last phase, the practical application of physiological psychology, including psychotherapy, is only at its commencement.

But while this last great movement has not yet reached its end, the new idealistic movement to come has not yet reached a clear self-expression. A general philosophical interest can be felt, but a great philosophical synthesis seems still lacking. A new sense of duty can vaguely be felt, but great new tasks have not yet found common acknowledgment. Above all, the unshaped emotionalism of the masses has not yet been brought into any real contact with the new idealism which grows up on the higher level of scholarly thought. But it is evident, if a new great mood of idealism is to come, one of its popular forerunners must be the demand that the spirit is real in a higher sense than matter, that the mind controls the body, that faith can cure. In such unphilosophic crudeness, no definite thought is expressed, as everything would depend on the definition of spirit, of faith, of mind, of reality. Moreover, every inquiry would prove that the idealistic value of such statements as are afloat among the masses to-day is reached only by a juggling with words. That faith can cure appears to point towards the higher world, as the word faith has there the connotation of the faith in a religious sense; and yet the faith which really cures a digestive trouble, for instance, is the faith in the final overcoming of the intestinal disturbance, an idea which belongs evidently in the region of physiological psychology, but not in the region of the church. Yet, however clumsy such statements may be, they are surely controlled by the instinctive desire for a new idealistic order of our life, and the time will come when their unreasoning and unreasonable wisdom will be transformed into sound philosophy without losing its deepest impulse. The realistic conviction that even the mind is completely controlled by natural laws and the idealistic inspiration that the mind of man has in its freedom mastery over the body, are thus most curiously mixed in the popular psychotherapy of the day, and too few recognize that the real meaning of mind is an entirely different one in these two propositions.

Of course the one or the other of these two elements prevails in the systematic treatises on the subject; the realistic one in those written by the psychiatrists, the idealistic one in those written by clergymen or Christian Scientists. The literature indeed is almost entirely supplied from these two quarters: and yet it is evident that neither the one nor the other party can give to the problem its most natural setting. The student of mental diseases naturally emphasizes the abnormal features of the situation, and thus brings the psychotherapeutic process too much into the neighborhood of pathology. Psychotherapy became in such hands essentially a study of hypnotism, with especial interest in its relation to hysteria and similar diseases. The much more essential relation of psychotherapy to the normal mental life, the relation of suggestion and hypnotism to the normal functions seemed too often neglected. Whoever wants to influence the mind in the interest of the patient, must in the first place be in intimate contact with psychology. On the other hand, the minister's spiritual interest brings the facts nearer to religion than they really are. That a suggestion to get rid of toothache, or to sleep the next night, is given by a minister, does not constitute it as a religious suggestion. If the belief in religion simply lies alongside of the belief in most trivial effects, and both are applied in the same way for curing the sick, it is evident that not the spiritual meaning of religion is responsible for the cure, but the psychological process of believing. But if that is the case, it is clear that here again the psychologist, and not the moralist, will give the correct account of the real process involved.In short, it is psychology, psychology in its scientific modern form, which has to furnish the basis for a full understanding of psychotherapy. From psychology it cannot be difficult to bridge over to the medical interests, on the one side, to the idealistic ones on the other side.

Our task here is, therefore, to lay a broad psychological foundation. We must carefully inquire how the modern psychologist looks on mental life and how the inner experiences appear from such a psychological standpoint. The first chapters of this volume may appear like a long, tiresome way around before we come to our goal, the study of the psychotherapeutic agencies. And yet it is the only possible way to overcome the superficiality with which the discussion is too often carried on; we must understand exactly how the psychological analysis and explanation of the scientist differ from the popular point of view. After studying in this spirit the foundation of psychotherapy, we shall carefully examine the practical work, its methods and its results, its possibilities and its limitations. We shall inquire finally into the place which it has to take, looking back upon its history, criticising the present status and outlining the development which has to set in for the future, if a haphazard zigzag movement is not to destroy this great agency for human welfare by transforming it into a source of superstition and bodily danger.