what important event does claudia tell readers about at the very beginning of the novel?

Claudia tells us that "quiet as it's kept," in the fall of 1941, when she was a young girl, no marigolds bloomed. She reveals that at the time she and her sister Frieda thought the marigolds did not bloom because Pecola was having her father's baby. The marigolds planted by Claudia and Frieda never grow, and for years Claudia thought that her sister was right in blaming her, because she was the one who planted the seeds too deep in the earth. But now, the narrator wonders if perhaps it was the earth itself that was barren. Claudia connects the earth to Pecola, saying that just as the MacTeer daughters put seeds into their plot of black dirt, Pecola's father dropped his seeds in his plot of black dirt. Now, with the flowers and the baby dead, only Pecola and the barren earth are left. The prelude closes by wondering about the source of Pecola's tragedy: "There is really nothing more to say‹except why. But since why is difficult to handled, one must take refuge in how."