The world of the grotesque is the darkness within us. Well before Freud and Jung shined a light on the workings of the subconscious, this correlation between darkness and our subconscious, these two forms of darkness, was obvious to people. It wasn't a metaphor, even. If you trace it back further, it wasn't even a correlation. Until Edison invented the electric light, most of the world was totally covered in darkness. The physical darkness outside and the inner darkness of the soul were mixed together, with no boundary separating the two. They were directly linked. Like this.