About Jung's Cross of Psychic Functions:
I believe that sensation and feeling belong to primitive functions, with a narrow evolutionary space, while intuition and thinking belong to acquired functions, with a vast evolutionary space. If we assign scores to each function of all individuals and mark them on a numerical axis, they will form distribution intervals of different lengths. The former has a very narrow distribution interval, say 5~10, while the latter has a very wide distribution interval, potentially reaching ranges like 5000~10000. Jung's concept of inferior functions only applies to comparisons between an individual's four functions; when comparing different individuals, the former (sensation and feeling) does not show significant differences, while the latter (intuition and thinking) may have substantial disparities.
Reading Jung's "Symbolic Life" Lecture 1, 29 reflections