The Only Story

Throughout the entire story, Steinbeck makes a point of noting the constant struggle for man to resist the temptations of evil,"There is no other story. A man, after he has brushed off the dust and chips of his life, will have left only the hard, clean questions: Was it good or was it evil? Have I done well—or ill?" (413). Steinbeck does this through his depictions of the characters in East of Eden, as they all struggle somewhat even if they don't say it outright, with few characters representing the idea of there being only good in the world and the refusal to believe otherwise and vice versa.
A main example would be Cathy, as she accepts her role in the world to cause pain to others with no end or goal to her personal gain, and she does this because she believes there to be no good to exist anywhere in the world and her goal in life is to do her best to survive.
The opposing force to Cathy would probably be Aron Trask, and I purposefully do not say any of the Hamiltons because, although they are extremely religious and base their lives off of God, they are aware of the evils in the world as they must know what is a temptation by the devil and what to avoid. Aron Trask, on the other hand, is kind-hearted to the point of naivety. He not only does not want to believe there is evil in the world, but does not have the ability to believe it, demonstrated by the fact that when Cal cruelly admits the truth to his brother about their mother, Aron ends up running off to the war and his death rather than face the fact that his mother is pure evil.
The rest of the characters have been shown to struggle between the paths of good and evil, as they are not straight lines. This is especially depicted by Cal Trask, as he was born of the evil nature he shares with his mother and uncle (father?), but constantly tries to better himself by following his brother's example. He is especially helped by Lee, the Trask's housekeeper, by proving to be the voice of reason.
However, there is also a large part of this novel involving the idea of having a choice in regards to whether or not you overcome sin. Eve can blame the snake all she wants, but in the end she was the only who decided to eat the forbidden fruit off the Tree of Knowledge after God explicitly told her not to, and the same principle applies. In Chapter 24, Lee speaks of timshel, "But the Hebrew word, the word timshel—'Thou mayest'—that gives a choice" (303), which was the word that God spoke to Cain before exiling him to Nod. Typically, the word orders men to triumph over sin, while another version says the word promises they will. Only the Hebrew version offers a choice, which is what Lee uses to convince Cal to stray from evil, because he knows Cal wants to do all he can to be a good man and not be the person his mother always was.
This connects to the symbol I defined from earlier, the inherited fortunes and how they symbolized original sin. Two out of three of those fortunes went to more than one person, and only one person out of each pair ended up being of evil nature, while the other was Adam. Adam chose to live an honest life and attempt to be as good a man as he could manage, rather than become the men his father and brother were. This proves that although the money corrupted the Trask family, it is still possible to overcome the power of original sin and be the man you choose to be.
This is also proved by the end of the novel just after his father dies, Cal is finally free to do what he chooses with his life. It is emphasized by the fact that Cathy and Aron have both already died, which were the two strongest forces of good and evil in the novel and both in his immediate family. Without the constant struggle of goof and evil in his family tormenting him and his father holding him back anymore, Cal can finally move on with his life and begin his own story with Abra. The season, not coincidentally, happens to be spring when this occurs, symbolizing rebirth and new beginnings that are ahead for Cal and Abra.

When it came to how I read the text, I specifically utilized certain lessons from Nabakov and Foster. From Nabakov, I found myself constantly recalling his lesson regarding the approach to literature, and how it should come unbiased and without any sort of background knowledge one may have heard regarding the text. I found this slightly difficult, considering the description on the back of the book provided me with the intertextuality relationship I ended up analyzing, rather than me discovering it for myself. I believe if I discovered the relationship for myself, it would've been much more difficult, but I may have been able to recognize the significant components of the novel that contributed to the theme/relationship rather than making possible assumptions due to the fact that I was unconsciously searching for connections. 
When it came to Foster, his examination regarding connections to the Bible and symbolism in nature were quite significant in my own analysis. The connection to the Bible was provided for me, as I said before, but his chapter on the Bible aided me in my search for various ways in which Steinbeck could use language and rhetorical techniques to connect back to that basic reference. The analysis of the mountains, the Gabilans and Santa Lucias, was my first inkling into the basic theme of the novel, and ended up becoming the base of my thought for the idea of the struggle for man to overcome the temptations of evil to be the basis of East of Eden.