Final answer:
The question pertains to the themes expressed in a series of narratives that revolve around memory, the supernatural, and the human experience. Agatha's thoughts about what happens every four years are not explicitly addressed but are inferred to relate to these broader themes.
Step-by-step explanation:
The question posed alludes to a story where a character named Agatha is contemplating what truly occurs every four years. The details provided in the various excerpts point to a collection of narratives that touch upon themes of memory, the supernatural, grim realities, and societal conflicts. While no direct answer is given regarding Agatha's specific thoughts, the snippets suggest a collage of historical and psychological motifs present in the respective stories they represent. The blending of different worlds, the impact of the past on the present, and the unseen forces that shape environments emerge as key elements. A common thread in these narratives is the exploration of human experiences and perceptions, both physical and ethereal.