The world was created, but there are two forces, arguing with each other in an eternal struggle

One of them is a centrifugal flow - Dinur, the individual elements of which are "materializing" spirits - Angels

The second one is the desire of the "lower" worlds to merge back into the "upper" ones gives rise to an opposing centripetal flow - the dematerializing forces of Demons

However, not having a source of Power in the form of the direct Light of a Deity, these spirits are forced to be content only with Light, which they can take away from the inhabitants of the "lower" worlds, that is, by engaging in predation