As I Lay Dying explores obligation to the family as well as to honor and principles. But the story’s principle plot line – a family’s lengthy journey to town from the country – is essentially only masked by the guise of duty. Supposedly the trip is to honor the wishes of a dead woman, but the patriarch’s reasons are ultimately selfish. Familial obligations create resentment in more ways than one, most noticeably for the family’s matriarch, who despises her duty to have children and play wife to a husband she can’t stand.
Cash is the only Bundren to act according to the other family members’ wishes.
Each member of the Bundren family focuses on an artificial or trivial "duty" to distract himself from the pain of Addie’s death.