In this excerpt from "The Big Rock Candy Mountain," Wallace Stegner conveys that understanding a person involves tracing their lineage and evolutionary history. He emphasizes that individuals are dynamic, constantly evolving rather than being fixed entities. This view suggests that a person's essence cannot be fully captured by mere analysis or classification because they embody the cumulative experiences and traits of their ancestors.

Stegner further illustrates that there is no definitive starting point for an individual, as their existence extends back to the origins of life itself. He likens humanity to an endless curve on a graph, highlighting the complexity and interconnectedness of our experiences. Ultimately, the study of mankind reveals the intricate tapestry of personal histories, emphasizing the challenge of fully comprehending any one person's journey.