Darkness has no shadow
Throughout history the shadow seems to represent a sort of duality between good and evil. From demons to spirits, they all reside and grow in the darkness of our shadows. It is a grounded fear, since darkness is the home of things we cannot see. Whether it be beasts or creations of the mind, darkness shrouds the reality we cannot see. The negativity of the shadow thus finds its roots in our fear of the dark.
However, there is a major difference between shadows and darkness. Total darkness exists because of the absence of light. Without light there can be no shadow and without shadows there could be no light, as the absence of shadows means there is no light to create the shadows. We see this phenomenon described in the novel The Late Mattia Pascal written by Luigi Pirandello in 1904...