The high priest is the anointed awareness within, the higher self that does not stand apart from the struggling flesh but has passed through every pull the body knows. It has felt the whole range of appetite and fear from the inside, tempted at every point where a person is tempted, and so it understands the lower nature it means to lift.
Yet it came through untouched by the missing of the mark, kept whole because it never mistook the pull for its own identity. This is the part of a person that already carries the answer, having crossed the same ground the body crosses and knowing its weakness from within.
High priest: the anointed higher self within, the mediating consciousness that has crossed the flesh's every trial without being owned by it