In medical terms, Freud’s achievements are on the whole limited to the fields of hysteria and obsessional neurosis.
His investigations begin with the psychogenetic explanation of the hysterical symptom, an explanation formulated by Mobius and experimentally tested by Pierre Janet.
According to this point of view, every physical symptom of a hysterical nature is causally connected with a corresponding psychological event.
This view can be corroborated by a critical analysis of the hysterical symptom, which becomes intelligible only when the psychological factor is taken into account, as exemplified by the many paradoxical phenomena of cutaneous and sensory anesthesias.
But the theory of psychogenesis cannot explain the individual determinants of the hysterical symptom.
Stimulated by Breuer’s discovery of a psychological connection, Freud bridged this large gap in our knowledge by his method of psychanalysis, and he demonstrated that a determining psychological factor can be found for every symptom.
The determination always proceeds from a repressed feeling-toned complex of representations.
(Lecturer illustrates this statement with a few case histories taken partly from Freud, partly from his own experience.)
The same principle applies to the obsessional neurosis, the individual manifestation of which is determined by very similar mechanisms. (Lecturer adduces a number of examples.)
As Freud maintains, sexuality in the widest sense plays a significant role in the genesis of a neurosis, quite understandably so, since sexuality plays an important role in the intimate life of the psyche.
Psychanalysis, in addition, has in many cases an unmistakable therapeutic effect, which however does not mean that it is the only way of treating a neurosis.
By dint of his theory of psychological determination, Freud has become very important for psychiatry, especially for the elucidation of the symptoms, so far completely unintelligible, of dementia praecox.
Analysis of this disease uncovers the same psychological mechanisms that are at work in the neuroses, and thus makes us understand the individual forms of illusionary ideas, hallucinations, paraesthesias, and bizarre hebephrenic fantasies.
A vast area of psychiatry, up until now totally dark, is thus suddenly illuminated.
(Lecturer relates two case histories of dementia praecox as examples.) ~Carl Jung, CW 18, Pages 388-389