Last week’s brouhaha about shifting zodiac signs brought to mind the subject of the nature and origin of personalities, specifically the thoughts of the great analyst Carl Jung, he of synchronicity, the collective unconscious, and the idea of introversion and extroversion defining us as human beings.

I’ve always gravitated to the Jung principles; easier to relate to in a present tense, and somehow more tied to the intrinsic “self” than Freud’s emphasis on infant/childhood experiences. (Jung addresses the divergences directly in the indispensable Modern Man in Search of a Soul, in the chapter, “Freud and Jung – Contrasts.”) In Jungian jargon, I’m considered an “INTJ” (Introversion/ INtuition/Thinking/Judgment) personality (per the Myers-Briggs Type Indicator (MBTI, based on Jung typology), probably as valid a classification as any. (Take a similar test here.)

More involving is Jung’s complex hypothesis of the “anima,” or life force.  The core aspect of the introversion/extroversion (“in/out”) theory is that the introvert’s essential spirit feeds on solitude; the extrovert’s on interaction with others. The introvert recharges in aloneness; conversely, the battery for the extrovert is drained without continual social stimuli. Jung writes that, “One cannot be introverted or extroverted without being so in every respect.” (Ambiverts beware…no middle of the road allowed.)

And the search for self continues…