What made Nyowe remember the story of a tortoise and the song that her mother usually sang

Nwoye preferred the stories his mother told, stories about "the tortoise and his wily ways, and the bird of eneke-nti-oba," rather than the violent stories his father shared with them. He continued to listen to Okonkwo's stories because he understood that it "was right to be masculine and violent."I think he remembers the stories when he is stressed and forced to act against his own nature.