But interest in suggestion does not represent to-day the last step of psychotherapy. The latest movement, which is entirely in its beginning, the development of which no one can foresee, but which promises wide perspectives, is connected with the name of Freud in Vienna. The entirely new turn of psychotherapy is given by the fact that his aim is not to overcome a symptom by suggestion but to make it disappear by removing the ultimate mental cause. He found that large groups of mental disturbances result from a psychical trauma, a disagreeable idea which, inhibited in the mind, becomes the source of mischief and produces phobias and obsessions and hysterical motions. The cure of the symptoms demands the recognition of this first mental accident, which may lie back for years and which may no longer be in the memory of the patient. As soon as this earlier experience is brought to consciousness again, it needs only a natural discharge and a normal expression and the symptoms which it brought about will disappear. Thus the cure itself needs no hypnotism and no persuasion or suggestion but the reawakening of forgotten situations, and only in the service of this effort hypnotism may be used to reenforce the memory. Yet this represents only the first period of Freud's activity, in which he collaborated with Breuer, a phase which is represented by their book on hysteria, in 1895. But there followed a further development which is still more essential. The hysterical disturbance may indeed have started with such an accidental traumatic impression but that does not explain why just this impression had such a strong effect. Other impressions of equal strength and emotional vividness may have passed without leaving any damaging result. And therefore there must be some prior cause in the subject which makes just this particular impression so injurious; and here is the point of Freud's fundamental discovery, which for the layman appears on the surface to have little probability but which has proved of greatest consequence for clinical work. It was found that only those situations become injurious and become starting points for hysterical symptoms which touch on repressed and artificially inhibited ideas of the sexual sphere.