When a neurosis breaks out in an adult, the fantasy world of childhood reappears

When a neurosis breaks out in an adult, the fantasy world of childhood reappears, and one is tempted to explain the onset of the neurosis causally, as due to the presence of infantile fantasies.

But that does not explain why the fantasies did not develop any pathological effects during the interim period.

These effects develop only when the individual comes up against a situation which he cannot overcome by conscious means.

The resultant standstill in the development of personality opens a sluice for infantile fantasies, which, of course, are latent in everybody but do not display any activity so long as the conscious personality can continue on its way unimpeded.

When the fantasies reach a certain level of intensity, they begin to break through into consciousness and create a conflict situation that becomes perceptible to the patient himself, splitting him into two personalities with different characters.

The dissociation, however, had been prepared long before in the unconscious, when the energy flowing off from consciousness (because unused) strengthened the negative qualities of the unconscious personality, and particularly its infantile traits. ~Carl Jung, The Undiscovered Self, Page 47