The medium can do nothing beyond receiving weakly what is implanted in him, for he is no longer in a positive purposeful state of activity. He has lost his own individual selfhood, and especially his power of logical rational thinking. Thus he lies at the mercy of whatever entity or whatever subconscious image overshadows him. The danger is that malevolent forces may take hold of him and make him their captive.
-- Notebooks Category 16: The Sensitives > Chapter 13: The Occult > # 148