The reasons why step-parent/child sex is bad for individuals is one of the themes Euripides wants to explore. Phaedra wants to go to bed with Hippolytus but of course she hasn't because she's his step-mother. Still, she has erotic feelings for him that she can't ignore. The way Phaedra sees herself is:
"My hands are pure but my soul is stained."In other words, merely to have these thoughts is wrong, regardless if the sexual desire for Hippolytus is ever fulfilled. She shouldn't even be thinking about him that way. As for Hippolytus, he's so pure that when he finds out about her desire for him he says:
"how could I commit so foul a crime when by the very mention of it I feel polluted?"It's wrong for fathers and sons to sleep with the same woman or mothers and daughters to sleep with the same man. Why? Some folks say it's wrong because the Bible says so. Others say it's wrong because it's against the law. Still others point out that we just know that it's wrong-- instinctively-- even if we can't say why. We just know it.
But all this focus on sexual relationships is really just a means for Euripides to explore a much bigger problem: What are human beings capable of? Can we excel like gods or are we limited? If we're limited then how much can we really change? Can we even control our own thoughts; much less change the whole world? Greek philosophers like Plato and Aristotle set very high standards for human achievement. The sky's the limit. Euripides seems more modest when he says:
"Men shouldn't aim for excessive perfection in life; for they cannot with exactness finish even the roof that covers a house..."This compassionate view of human nature sets the tone of the whole play: we should consider the human heart in all its complexity before passing judgment. Question: should we condemn Phaedra because she has sexual longings for her stepson Hippolytus? Perhaps she can control what she does but can she control what she feels?
One way of looking at Phaedra is to view her through the prism of the Greek gods. In this view she's merely a pawn in a game that Venus is playing. Venus is the goddess of love and Hippolytus disrespects her when he says that
"I can never satisfy my hate for women."Venus wants revenge on Hippolytus so Phaedra's "heart is crushed, cruelly afflicted by Venus with unholy love." Phaedra's nurse catches wind of what's going on and at first she's shocked. But after she thinks about it awhile she tells Phaedra: "Your fate isn't unusual ...you're stricken by the passion Venus sends. You're in love; so what? So are many more." Euripides' message seems to be: we're all human; the human heart is a complex thing and we often have desires we can't control. 2500 years later a psychologist named Freud would come to the same conclusion.