in so far the body or in fact all of concrete reality is understood as consisting of qualities, this understanding is generated by sensation. understanding of movements and processes is generated by intuition. introversion and extroversion a probably mainly associative processes, meaning how attention wanders through the territory of, in this case, sensation or intuition. in the case of extroversion the mind studies the relationships between internal and external qualities or processes. in the case of introversion it studies the intrinsic preferences (S) or flows (N). another aspect of introversion and extroversion may be summarizing of complexities into whole pictures. it results from associative experience. for instance, if seen through Si, you perceive as your own that which is fairly constant about you (intrinsic preferences) and whatever changes may be interpreted as influence of the environment, through Ne. whereas in the case of Ni+Se, there is a scanning for familiar (in that sense relatively constant) processes and these are perceived as your own being and static aspects of physical reality are associated with the objective world. to put it in less analytic language, the Ne&Si types might formulate: my body is a lump of various organic qualities of clay, all animated by the world's winds of change. and Ni&Se types might formulate: my being is the living energy of the source, manifesting the body and the world as a mere image of itself. you can see why the former would have a tendency to become askets trying to transcend the body and enter a dream like, fully animated, liberated, reality of noself, while the latter would obsess about kundalini or the likes and becoming one with some intimate principle of higher order, the "SELF", or manifestation. in either case intuition/process is associated with pure life, at least from the POF of intuitive philosophers or gurus, but sensation is an integral aspect of it, there cannot be life without the experience of qualities. only the mind is dissecting reality into it's aspect. of course true awakening transcends the illusion of such separations, but most people are just in the process of awakening, hence philosophies and spiritual teachings reflect those typological biasses.
sincerly9000