“There are beings in the spiritual realms for whom anxiety and fear emanating from human beings offer welcome food. When humans have no anxiety and fear, then these creatures starve. People not yet sufficiently convinced of this statement could understand it to be meant comparatively only. But for those who are familiar with this phenomenon, it is a reality. If fear and anxiety radiates from people and they break out in panic, then these creatures find welcome nutrition and they become more and more powerful. These beings are hostile towards humanity.
Everything that feeds on negative feelings, on anxiety, fear and superstition, despair or doubt, are in reality hostile forces in supersensible worlds, launching cruel attacks on human beings, while they are being fed. Therefore, it is above all necessary to begin with that the person who enters the spiritual world overcomes fear, feelings of helplessness, despair and anxiety. But these are exactly the feelings that belong to contemporary culture and materialism; because it estranges people from the spiritual world, it is especially suited to evoke hopelessness and fear of the unknown in people, thereby calling up the above mentioned hostile forces against them.”
~ Rudolf Steiner [Source (German): Rudolf Steiner – Die Erkenntnis der Seele und des Geistes – Berlin, 1907]