ENANTIODROMIA PRINCIPLE / ENANTIODROMIA is the ideas that the superabundance of any force inevitably produces its opposite -- psychically transmogrifies into its shadow opposite, in the repression of psychic forces that are thereby cathected into
something powerful and threatening.
Jung used the term particularly to refer to the unconscious acting against the wishes of the conscious mind. (Aspects of the Masculine, chapter 7, paragraph 294).
"Enantiodromia. Literally, "running counter to," referring to the emergence of the unconscious opposite in the course of time. This characteristic phenomenon practically always occurs when an extreme, one-sided tendency dominates conscious life; in time an equally powerful counterposition is built up, which first inhibits the conscious performance and subsequently breaks through the conscious control." -- Carl Jung ("Definitions," ibid., par. 709)
Enantiodromia is typically experienced in conjunction with symptoms associated with acute neurosis, and often foreshadows a rebirth of the personality.
"The grand plan on which the unconscious life of the psyche is constructed is so inaccessible
to our understanding that we can never know what evil may not be necessary in order to produce good by enantiodromia, and what good may very possibly lead to evil."
-- Carl Jung ("The Phenomenology of the Spirit in Fairytales", Collected Works 9i, par. 397)
Enantiodromia also refers to the process whereby one seeks out and embraces an opposing quality from within, internalizing it in a way that results in individual wholeness. This process is the crux of Jung's notion called the "path of individuation." One must incorporate an opposing archetype into their psyche to obtain a state of internal 'completion.'