one soon comes to a frontier, or rather to frontiers which recede behind one another presumably up to the point of death. The experience of these frontiers gradually brings the conviction that what is experienced is an endless approximation.
Jung, via Edinger, defines the frontier as the receding limiting threshold of psychic approximation toward the unknowable Self-centre, multiplying serially until death.
, The New God-Image: A Study of Jung’s Key Letters Concerning the Evolution of the Western God-Image, 1996thesis