Steinbeck opens by establishing the Salinas Valley setting and the two central families — the Trasks and the Hamiltons — whose intertwined histories across generations will reenact the biblical story of Cain and Abel in various forms throughout the novel.

Key elements established in the opening:

• The novel's rich, almost mythic descriptions of the Salinas Valley establish setting as a central character in its own right, framing the human drama against a larger natural and historical backdrop
• Adam Trask's troubled relationship with his brother Charles, marked by their father's clear favoritism, establishes the first of the novel's several Cain-and-Abel-patterned sibling rivalries
• Samuel Hamilton, based on Steinbeck's own grandfather, is introduced as a wise, warm counterpoint to the Trask family's darker patterns, providing much of the novel's moral grounding

This opening establishes both the sweeping generational scope and the biblical allegorical structure that organizes the rest of the novel.