The pathway of the mystical goal is strewn with human wreckage. Why? Several reasons would be needed to give a complete answer but one of the most important is this: Between the state of ordinary man and the state of the matured mystic there lies a perilous and deceptive psychological region which has been given various names in mystical literature. It has been called the astral plane, the intermediate zone, the hall of illusion, and so on. The early efforts of all aspirants in concentration, meditation, self-conquest, and study, bring them into this region. But once here their egoism becomes stimulated by the subtle forces they have evoked, their emotional nature becomes more sensitive and more fluid, their imaginative power becomes more active and is less restrained. The consequence of failure to negotiate these changes properly is swollen vanity, superstitious credulity, emotions run riot, and imagination gone wild. The safeguards against all this are first, submission to the philosophic discipline and second, submission to competent guidance.
-- Notebooks Category 16: The Sensitives > Chapter 12: The Intermediate Zone > # 1