In "The Yellow Wallpaper" by Charlotte Perkins Gilman the unnamed protagonist is obsessed with the yellow wallpaper because it represents the insanity in her life that snowballs from post pardum depression to a serious nervous disorder. .
When we first learn of the protagonist, we find she suffers from post pardum depression, which her husband, a high ranking doctor, attempts to address by treating her with a "Rest-cure" (pg. 617) by placing her in a colonial mansion away from society. It is this location where she comes in contact with the yellow wallpaper. Automatically when the narrator views the yellow wallpaper of the room, she is appalled at the way it looks. She states she had never seen worse paper, and that it had "committed every artistic sin." (pg. 618) .
We learn of her resentfulness of the wallpaper through writings in her journal. She is not allowed to visit her Cousin Henry or Julia, her husband is gone most of the day and she is not allowed to leave the room, which leads her to discuss the wallpaper, or in reality her portrait of herself. She talks of how horrid it is and a spot where there is a bump in the pattern that looks like a broken neck. This represents her dissatisfaction with her life. She cannot overcome the wretchedness of the paper because she cannot overcome her own problems. She believes the wallpaper looks at her "as if it knew what a vicious influence it had." (pg. 620) This represents the tremendous impact the depression has on her life and her refusal to accept her inner chaos.
Her simple hate of the wallpaper grows into a hallucination of images that emerge from it when she begins to realize her need for help. She begins to see "a strange, provoking, formless sort of figure." (pg. 621) This shows that the narrator is inwardly analyzing herself as well as her illness and yet she still cannot come to terms with it. She says the wallpaper has no laws, and everything that makes up the wallpaper consists of things of which she has never heard.