What are all the themese in "Rappaccinis Daughter"?

One major theme of this story is the idea that human beings are a mixture of good and evil and that we cannot exist without one or the other. We are, by our natures, both.
Beatrice, for example, seems so good and sweet and kind, but poison is a part of her makeup, and when Giovanni attempts to remove this "evil" and destructive part of her, she dies because a human being cannot be all good—it is simply not within our nature to be so. Giovanni, likewise, seems good when he loves Beatrice, but he turns cold and dissatisfied with her. He cannot love her as she is, good and bad, and so he attempts to change her, to perfect her. In doing so, he strips her of her nature and brings about her death.