The complex relationship between autobiography and biography is a central theme in The Stone Diaries. While autobiography provides a first-person account of one's own life, biography offers a third-person perspective on someone else's life. These two forms form the backbone and essence of the novel. The story delves into whether such narratives can ever truly provide a complete and accurate representation of a person's entire life or their evolving character. The novel suggests that any written account is always less than the full story, never capturing the complete personality or psyche as it changes over time. For example, when summarizing Cuyler Goodwill's early years, the narrator observes: "The recounting of a life is a cheat … our own stories are obscenely distorted." Regardless of how the story is told, it remains a condensed version of the total life experience. It cannot encompass everything and is not the life itself, but rather a narrative about the life. Life itself slips away moment by moment, with many experiences fading from memory even as they occur.

This feeling of disconnect from experiences, possessions, or one's own identity is countered by the imaginative process of writing a life story, which conjures, retrieves, and creates to fill in the gaps left by missing details. For instance, the narrator describes a time when young Daisy is ill and confined to her dim Winnipeg bedroom for weeks. The child realizes that life goes on outside her home, even though she is not part of it. Confined to her sick room, she feels "erased from the record of her own existence." To counter this sense of leaving no mark or not existing in the world, the narrator remarks about Daisy: "She understood that if she was going to hold on to her life at all, she would have to rescue it by a primary act of imagination, supplementing, modifying, summing up the necessary connections … getting the details wrong occasionally." Essentially, reflecting on one's experiences and self is an act of storytelling, much like writing fiction. The individual selects and edits life events, emphasizing some aspects while omitting others. Even among the remembered moments, not everything is included. Elsewhere, the narrator notes: "There are chapters in every life which are seldom read, and certainly not aloud." For various reasons, the storyteller censors certain material. Thus, in this fictional novel, autobiography and biography are explored to demonstrate how these forms of writing reinvent the life they aim to portray.