The narrator uses these words to introduce Cathy Ames in Chapter 8 of the novel. Throughout the novel, Cathy displays an evil that is so thorough that it borders on implausible, and the narrator makes several attempts to explain and understand Cathy’s existence. He hypothesizes that although Cathy is physically beautiful, she is a “psychic monster,” a being with a mental deformity analogous to others’ external, physical deformities. Later in the novel, the narrator revises his opinion of Cathy and wonders whether he was right in calling her a monster. He seems to become somewhat more sympathetic toward Cathy, musing that “since we cannot know what she wanted, we will never know whether or not she got it.” Indeed, Cathy’s motivations remain a mystery throughout East of Eden, as her schemes seem to have no concrete goal or aim—a problem that critics have singled out in their writings on Steinbeck’s novel.

Here, in Chapter 13, in another aside to the story, the narrator sets for his belief that the power of free will in the human mind is the most precious of human capabilities. He declares his intention to fight against any force—ideological, religious, political, or otherwise—that threatens to hinder or constrain this freedom of the individual. In highlighting the importance of free choice early in the novel, the narrator foreshadows the idea of timshel, or freedom to choose between good and evil, that becomes the main idea in East of Eden. Although Cal and other characters struggle with the problem of evil throughout the rest of the novel, the narrator plants a seed of hope early, in these words.

Lee says these words during his discussion of the Cain and Abel story with Samuel and Adam in Chapter 24. He has just revealed to the other men the outcome of the research he did on the meaning of timshel, the word that God utters to Cain when exiling him to the lands east of Eden. According to one translation of the Bible, God orders Cain to triumph over sin, while according to another, God promises Cain that he will defeat sin. Lee’s research, however, has revealed that timshel means “thou mayest,” implying that God tells Cain that he has a choice whether or not to overcome sin. Lee sees this idea of free choice over evil a token of optimism that is central to the human condition. He attempts to convince Adam and Cal of the validity of timshel and ultimately succeeds, as Adam gives Cal his blessing and Cal realizes he himself has the power to overcome his family’s legacy of evil.

In Chapter 34 of East of Eden, the narrator discusses his view that the one central narrative in human history is the endless struggle between good and evil. He believes that this recurring conflict is so important to human history that there essentially “is no other story.” Each individual, regardless of what his or her ancestors have learned, struggles with the same fundamental problem of evil. In this way, no progress is made as generations pass, for each individual faces the same ancient struggle and the same ancient choices. Although the narrator’s idea is somewhat optimistic in that it implies that each individual has free will to reject evil, it also implies that the struggle with evil is endless and inescapable and will therefore always be a part of the human condition.

This exchange between Adam and Cal, which appears in Chapter 51, is a direct parallel with the exchange between God and Cain that appears in the book of Genesis in the Bible. After Cain murders Abel, God realizes that Abel is missing and asks Cain where Abel is. Cain retorts, “I know not; am I my brother’s keeper?” Adam and Cal’s reenactment of this conversation links them explicitly to the biblical story and cements Cal and Aron, respectively, as surrogates for Cain and Abel. There are differences between the two stories, however: whereas Cain murders Abel, Cal causes Aron’s death only indirectly. Likewise, whereas Cain is banished for his crime, Cal encounters forgiveness and redemption in his father’s blessing at the end of East of Eden. In this way, Cal, though a Cain figure, overturns the biblical story and, in the end, demonstrates that he has the power to choose good.