Note: Cathy's name switches halfway through the novel. We refer to her based on what she is going by at the particular moment in the book we're discussing.
Where do we begin with Cathy? Steinbeck calls her a monster, and everybody else seems to think that she's the evilest thing that ever walked the earth. It's not a very flattering view of Eve, now is it?
To be fair, Cathy does bring it on herself every now and again. Sure, she murders people without batting an eyelash, and she enjoys emotionally manipulating people just for kicks, but it's hard not to sympathize with her at times; it seems like everyone around her wants to make her into their own ideal Cathy, and she is having none of it.
Steinbeck gives us a lot of shoulder-shrug explanations about why Cathy just hates all of humankind with a burning passion. But before we get to all that, let's see what Cathy herself has to say about the matter:
"They thought they were so smart," she said. "They looked at me and thought they knew about me. And I fooled them. I fooled every one of them. And when they thought they could tell me what to do—oh! that's when I fooled them best." (39.2.90)
Okay—so Cathy is bored with the stupid people around her. Fair enough. She seems to be a cut above the rest with how cunning and smart she is, though that doesn't really justify murdering people.
At the same time though, the novel seems to suggest that for all her wily intellect she is actually lacking something that the rest of humanity has. Here is what Adam says to her when he confronts her in the whorehouse:
"I know what you hate. You hate something in them you can't understand. You don't hate their evil. You hate the good in them you can't get at. I wonder what you want, what final thing." (25.3.129)
And then here is what Cal says to her a little later:
"did you ever have the feeling like you were missing something? Like as if the others knew something you didn't—like a secret they wouldn't tell you?" (39.2.98)
What is Cathy missing? Adam might just have hit the nail on the head when he says that Cathy can't understand basic human goodness. See, Cathy thinks the world is full of hypocrites. It makes sense, because she deals with the part of human nature that people tend to hide and be ashamed of: their sexual side (which we'll talk about some more below).
Steinbeck's favorite moniker for Cathy by far is monster. But what is a monster? According to Steinbeck, "Monsters are variations from the accepted normal to a greater or a less degree" (8.1.3). In other words, just like Adam and Cal suggest, Cathy has something wrong with her that makes her different from other people. But at the same time, it's a difference that we will never understand:
Perhaps we can't understand Cathy, but on the other hand we are capable of many things in all directions, of great virtues and great sins. And who in his mind has not probed the black water? (13.2.2)
So in short, for all her badness we shouldn't be too hard on Cathy. She may lack any semblance of a conscience whatsoever, but evil itself is not exclusive to her.
Speaking of evil, another big aspect of Cathy is that she plays the allegorical double for Eve. But oh what an unconventional Eve she makes.
Okay, so aside from the fact that she marries Adam, Cathy's main features are that she's pure evil and she is very sexual. The biblical Eve might not be evil, but she is the one who invites evil into the world by accepting a suspicious apple from a shady snake. Actually, it's not evil itself so much as the knowledge of good and evil. This is in keeping with Cathy as really smart, and really perspicacious when it comes to seeing the hypocrisy in bad people who pretend to be good (and it's also in keeping with Adam being dumb as a rock when it comes to telling good from bad).
And what is the first thing Adam and Eve realize after their little apple feast? They become ashamed of their nakedness (yeah, apparently Eden was like a nude beach). In other words, one of the first things the knowledge of evil brings is an aversion to openly expressing your sexuality. Cathy is an expert at manipulating this shame: she knows that people will act on their sexual urges and then feel remorse and humiliation for it. Which brings us to…
Plug your ears, kids. Things are about to get R-rated—R in this case for Real. One of the first things we are told about Cathy is that she knows how to use sex to her advantage; Cathy is a natural-born whore. We aren't talking about promiscuousness here; we mean that she is literally a prostitute. As in she trades sex for money. But the way she controls people isn't so much through sex itself as much as through other peoples's attitudes toward sex:
Cathy learned when she was very young that sexuality with all its attendant yearnings and pains, jealousies and taboos, is the most disturbing impulse humans have. And in that day it was even more disturbing than it is now, because the subject was unmentionable and unmentioned. Everyone concealed that little hell in himself, while publicly pretending it did not exist—and when he was caught up in it he was completely helpless. Cathy learned that by the manipulation and use of this one part of people she could gain and keep power over nearly anyone. (8.1.18)
Translation: people in the olden days (and now) don't like talking about sex or even acknowledging that it exists, while at the same time they are totally doing it, like, all the time. Cathy's power is that she realizes this about her society. We see her using the taboo associated with sex to ruin people all the time: from her Latin teacher who is so ashamed of his actions that he commits suicide to all the photographed bigwig patrons of her brothel.
Take Kate's little photo collection. Remember, Kate's whole umbrage with the world is that they are hypocrites when it comes to sex: On the one hand they act like moral, righteous people, and on the other hand they go to brothels and have a debauched old time. It's a recipe for power and control.
But looking at the passage above, can you guess what Steinbeck's attitude towards sex is? He seems to think that it would be great if we could just, you know, talk about sex and not act like it's a huge deal. At the same time, though, he vilifies someone like Cathy for making it into some kind of dehumanizing game.
But what if everyone stopped pretending? Cathy's incriminating photos might get destroyed in the novel, but it still forces us to consider the question of whether we should pretend that something as widespread as sex is really all that shameful.