In "East of Eden," John Steinbeck explores the inherent nature of human beings, suggesting that most people possess deep-rooted appetites and impulses. These instincts often trigger a wide range of emotions, showcasing a spectrum of human behavior that reflects our complex personality traits. The idea is that these impulses, though sometimes hidden, drive individuals in their decisions and interactions.

Steinbeck also highlights the concept of "islands of selfishness" within everyone. This suggests that underneath the surface of civility and social behavior lies a strong inclination toward lust and self-interest, making it a universal aspect of the human condition. The narrative delves into how these underlying traits influence personal choices and the moral dilemmas faced by characters.