The mood in East of Eden is highly variable, depending on the characters whose perspective and story Steinbeck chooses to highlight in any given chapter. As the narrator transitions from one character to another, Steinbeck must naturally modify narrative mood to blend with individual characters' circumstances. When discussing a character with interesting foibles, through the use of irony, East of Eden's narrator may introduce some humor or levity to the mood. However, in large part, the mood is serious and critical, focusing on the various acts of violence people commit against one another and the relative nature of morality.
East of Eden shares certain elements of mood with the biblical text that inspired it. Both books are heavy at times, fraught with strife and conflict, but both contain an enduring message of perseverance: in the Bible, this spirit of endurance accompanies God's promise to eventually send a savior (Jesus) to free everyone from their sin. This "promise" from God imbues much of the Bible following Genesis with a mood of expectant hope in the midst of suffering and exile. Steinbeck's approach towards expectant hope is much the same. At the turn of the 20th century, many societal changes occurred, leaving some people fearful, and others expectant and hopeful for the future.