Our mania for rational explanations obviously has its roots in our fear of metaphysics, for the two were always hostile brothers. Hence, anything unexpected that approaches us from the dark realm is regarded either as coming from outside and, therefore, as real, or else as a hallucination and, therefore, not true. The idea that anything could be real or true which does not come from outside has hardly begun to dawn on contemporary man.

The Collected Works of C.G. Jung: Civilization in transition (ed. 1964)