C.G.Jung

the case of normal people the principal function of the unconscious is to effect a compensation and thus produce a balance. All extreme conscious tendencies are softened and toned down through an effective opposite impulse in the unconscious

the normal functioning of the unconscious processes breaks through into the conscious mind in an abnormal manner, and thereby disturbs the adaptation of the individual to his environment.

The pairs of opposites are torn asunder, the resulting division or strife leads to disaster, for the unconscious soon begins to intrude itself violently upon the conscious processes. Then odd and peculiar thoughts and moods supervene, and not infrequently incipient forms of hallucination, which clearly bear the stamp of the internal conflict.