Joyce's Portrait has a very unique perspective on women through its protagonist, Stephen Dedalus. In the first chapter, there are only two women encountered in a significant way. These are his mother and Dante, a friend of the family. Dante had been a nun and Stephen's mother is a catholic. From Stephen's point of view, at his young and fragile age, these two women can be compared to the Virgin Mary for the sake of this discussion.
Joyce also describes a character by the name of Eileen Vance who lives next door to him and is Protestant. The second page of the novel finds Stephen hiding under the table because he has said that he would marry Eileen. Because she is Protestant and Stephen is Catholic, Dante threatens that if he does not apologize, "the eagles will come and pull out his eyes." This sets up Eileen as forbidden.
Eileen's forbidden nature relates to the prostitute that Stephen visits at the end of chapter two. At that point, we see Stephen has very extreme representations of women to work with. On one side is the Virgin Mary and on the other is prostitute. The ambiguous E.C. character falls at whichever end of the pendulum Stephen has found himself at that particular moment. When he fantasizes about her, she is likened to a prostitute. When he reveres her, comparing her to the "ivory tower," she can be compared to the Virgin Mary.
It's not until the end of chapter four when the extremes settle down and he can see a girl for what she is, a girl that doesn't have to be an extreme representation of women. He still thinks of her in a "worshipful" manner, but he is inspired by her. That's the difference that he sees and that is how he is able to overcome the extremes.