John Steinbeck includes more of the tale of Genesis: 4 than is actually told in the bible. The basis of this is a Jewish story involving twin sisters of both Cain and Abel. The two disputed over Abels twin whom Abel was to marry. Cain murdered Abel and wed the twin sister of his brother (Fonterose, Joseph. p.3380). The story differs also in that it is Abel who leaves his home instead of Cain. Abel found his Eden, represented by Salinas Valley, but lost it after fathering a second generation very similar to the first, Caleb representing Cain and Aron representing Abel (Fonterose, Joseph. p.3379). The story is changed by Steinbeck to illustrate the idea that men naturally have both good and evil tendencies within them, and that this mixture compels men to choose between the two. The story told is similar to an alternate interpretation of Genesis: 4 called timshel. This alternate reading introduces the idea that Cain feels evil and kills Abel because of the jealousy he feels towards his brother and Gods love for Abel (Levant, Howard. p.243).
The relationship of good to evil is found in many different ways throughout East of Eden. One way is the opposition between the two. Such a relationship is illustrated through the Cain and Abel allusions in the novel. Another relationship is that the two must coexist. This relation is represented by the arrival of both the church and the brothel in town at the same time. Good comes from evil is the third relationship. Cathy making Adam appear all the more pure shows this relation. The last relationship is that both terms are relative (Fonterose, Joseph. p.3381). Caleb Trask is illustrated as being a man more evil than others are. This innate wickedness varies from the immoral values of other characters such as Charles or Cathy-Kate. The wickedness is attributed to Calebs ability to choose between good and evil and his choosing of the latter (Levant, Howard. p.240). In East of Eden, good is associated with individual morals. Examples of such would be abstinence from sexual activity and virtues like generosity and self-respect. Evil is illustrated through acts such as prostitution and murder (Fonterose, Joseph. p. 3381). Sex is treated as a carnal act that cannot be good. It is a sin; where in other Steinbeck novels, it would be easily accepted. The sex in East of Eden is considered extremely bad and thus an evil action (Fonterose, Joseph. p.3381).
Steinbeck elucidates in East of Eden the belief that man, as a whole is a part of the continuous stream of good and evil. Where one man becomes condemned for his sloth, another might see the mark of Cain as a reason to persevere. Steinbeck states, using the character Lee, Cain bore the mark not to destroy him but to save himIt was a preserving mark. (Marks, Jay Lester. p.123). The major motifs in East of Eden are actually based on two independent thoughts. The first is based on who man is. It is a statement of how he lives his life. The second is the choice that man has between good and evil. These two thoughts are easily related and thus make up the motif (Marks, Jay Lester. p.120). Steinbecks belief that evil is not passed from parent to child is illustrated by Kate and her sons. Aron and Caleb are obviously nothing like their mother when it comes to the matter of good and evil. Aron, the Abel figure, is not capable of his mothers wickedness and lack of morality. Caleb differs from his mother in that he is heterogeneously good and evil. Caleb is the proof Steinbeck gives that man takes his own path and not necessarily the path of his bloodline (Marks, Jay Lester. p.127). Steinbecks interpretation of the timshel document suggests that the schism of moral values is illustrated in the story of Cain and Abel. Thus, good and evil are separated each having its own moral standpoint. Because of mans evil heritage, being descendent of Cain, he is naturally forgiven for any breach in purity