I am unable to maintain that the exertion of the will, in crowding such thoughts out of one’s mind, is a pathological act, nor am I able to state whether and how, the intentional forgetting succeeds in those persons who remain well under the same psychic influences. I only know that in the patients whom I analyzed such “forgetting” was unsuccessful and led to either a hysteria, obsession, or a hallucinatory psychosis. The ability to produce, by the exertion of the will one of these states all of which are connected with the splitting of consciousness, is to be considered as the expression of a pathological disposition, but it need not necessarily be identified with personal or hereditary “degeneration.” Over the road leading from the patient’s exertion of the will to the origin of a neurotic symptom I formed a conception which in the current psychological abstractions may be thus expressed: The task assumed by the defensive ego to treat the incompatible idea as “non arrivée” can not be directly accomplished. The memory trace as well as the affect adhering to the idea are here and can not be exterminated. The task can however, be brought to an approximate solution if it is possible to change the strong idea into a weak one and to take away the affect or sum of excitement which adheres to it. The weak idea will then exert almost no claims on the association work; but the separated sum of excitement must be utilized in another direction. Thus far the processes are the same in hysteria, in phobias and obsessions, but from now on their ways part. The unbearable idea in hysteria is rendered harmless because the sum of excitement is transformed into physical manifestations, a process for which I would like to propose the term conversion. The conversion may be total or partial, and follows that motor or sensory innervation which is either ultimately or more loosely connected with the traumatic experience. In this way the ego succeeds in freeing itself from opposition but instead it becomes burdened with a memory symbol which remains in consciousness as an unadjusted motor innervation, or as a constantly recurring hallucinatory sensation similar to a parasite. It thus remains fixed until a conversion takes place in the opposite direction. The memory symbol of the repressed idea does not perish, but from now on forms the nucleus for a second psychic group.