East of Eden: Theme Analysis

Good vs. Evil
Central to John Steinbeck's East of Eden is the theme of good versus evil. From the opening chapter, the author delineates the central structure of good and evil in the form of the symbolic landscape: the Edenic splendor of Salinas Valley in Northern California. The narrator learns to tell east with its "good" sunlit Gabilan Mountains from the western dark and foreboding "bad" Santa Lucias Mountains.
However, in addition to the symbolic landscape are the more or less symbolic characters that most deeply influence the protagonist, Adam Trask: Samuel Hamilton, who represents the epitome of goodness, and Cathy Ames, who signifies abject evil. Adam, the first man, or everyman, navigates life's valley wavering between good (light) and evil (dark) in the form of Samuel and Cathy.
Samuel Hamilton is the much-beloved and admired Hamilton family patriarch who acts as a mentor for Adam and stands in sharp contrast to his own father Cyrus, the dishonest Trask Family patriarch who committed the novel's "original sin," by lying about his military record and amassing a fortune he bequeaths to his sons, Adam and Charles. A self-educated immigrant from Northern Ireland who considers books to be treasures, Samuel is associated with light and demonstrates the positive principle of life. A good
father figure, he finds water and delivers babies. The progenitor of nine children himself, he walks in sunlight, moonlight and starlight. Water always surrounds him. He washes constantly. Samuel is one of the few characters who views Cathy for what she is-evil personified-and suffers a severe fever when she infects him with a bite.
Representative of Satan, the most evil character in the novel, Cathy is a parasite who embodies evil. She lacks the innate quality that makes one human. She murders her parents and becomes a notorious brothel owner who gives drugs to her whores, encourages sadomasochistic sexual practices and blackmails her customers. In opposition to Samuel, who is associated with light, she prefers the dark. While giving birth, she labors in a completely dark room, like an animal in a den. And, she is only comfortable during the latter part of her life in a gray tomb-like room void of light. And while Samuel
represents the positive loving father, she signifies the ultimate evil mother, or "anti-mother."  Her nipples are inverted, her breasts fail to produce milk, and she never looks at her babies that she abandons when they are a week old. And, while Samuel sinks into a comfortable life of retirement with his children caring for him, she commits suicide alone in her dark hole of a room. These two characters represent good and evil and most influence the protagonist Adam Trask. He is completely smitten by Cathy and cannot effectively continue his life after she leaves. His inherently good friend Samuel finally forces him to confront her as evil, and he comes away free for the first time in years. However, even at the end the shattered Adam still cries out "Oh, my poor darling," when he hears of her death.
Timshel
When Samuel visits Adam before he retires from his ranch, he comes across Cal and Aron, the twins he delivered eleven years earlier. Lee brings drinks and almost immediately, the story of Cain and Abel comes once again to mind and the three men take up the conversation they began ten years earlier when they puzzled over exactly why God had favored Abel's gift of the lamb over Cain's gift of the grain.  Similarly, after reading the sixteen verses of the biblical account, they had discussed the story at length and attempted to figure out what indeed God had promised Cain when he banished him from the sight of mankind. Was Cain predestined to everlasting damnation, or could he find redemption?
The philosopher Lee explains he has in the interim been studying the Cain and Abel story
with four aged Chinese gentlemen and a rabbi in San Francisco. One biblical translation, he informs them, maintains that God promises Cain that he will overcome sin, but another translation, puzzlingly posits the idea that God orders Cain to overcome sin. After years of research, the aged wise men happily conclude that both these translations are in error and that indeed the Hebrew word,timshel, the verb causing the discrepancy, actually means "thou mayest." Lee cannot contain his glee as Samuel comes first to grasp the meaning. Lee considers timshel to be a powerful idea about human free will, something that gives people the freedom to forge their own moral destinies. Thus, Cain actually was
imbued with the ability of free will, or free choice: God has given humans the power, or the ability, to choose goodness over evil.
At this point, Samuel utilizes the concept of timshel by choosing to help his friend Adam and informs him that Cathy, now known as Kate, is still in Salinas where she runs a notorious whorehouse. Lee acknowledges Samuel's message as truth. But Adam, unable to stand the pain, runs away in horror.
The concept of timshel remains of primary concern in Steinbeck's East of Eden. Simply put, timshel offers humans the ability to forget the past and forge a better life, a life of hope and redemption. No one, the idea insists, is predestined to choose evil despite the lives (evil or otherwise) lived by their parents. The concept of timshel becomes
particularly pertinent at the end of the novel during Aron's death. The despairing Cal believes in innate evil but is convinced by Lee otherwise, and during the final scene, Adam raises his hand in blessing to his son and utters the Hebrew verb:timshel. Cal and Abra, descendants of prostitutes and thieves, embrace the concept of timshel, "thou mayest," and thus attain the freedom of will to choose their own moral destinies.