rivalry. Sometimes twins can represent some "other" aspect of the "self"- either a doppelganger or a shadow. Often in mythology the twin is evil, or the other one may be human and the other is semi-divine. In cases where the "evil twin" is not physically distinguishable from the "good twin", a typical plot resolution will involve the banishment and unmasking of the "evil twin". In the modern usage, the words "evil twin" and "doppelganger", have come to be virtually interchangeable. While the evil twin does not connote the sense of "supernatural harbinger of death", it can be used to mean "a physical copy of one's self that has an altered morality". The supernatural aspects of the book often recur and the sightings of doppelgangers tense up the air. When Hester thinks she sees Adeline and Emmeline playing in the woods, she later says she must have seen a ghost. A doppelganger. The bond shared by Adeline and Emmeline is one of deep meaning. Only the two together, can you create a whole and the absence of one can cause great physical and emotional trauma. When Hester and Dr Maudsley experiment with original case study research, the separation of the twins is painful for all to see. It greatly affected the mental abilities of each twin. The heartfelt pain of losing not just a sibling, but a twin, the one who shared a bond deeper than any other. "She was lost, absent from herself. Without her sister, she was nothing and she was no one. It was just the shell of a person they took to the doctor's house." — p. 205. The separation also proved painful, it was no ordinary separation and each twin would have rather died than live on without the other. To them, there was just no point in living any more. "The separation of the twins was no ordinary separation. Imagine surviving an earthquake. When you come to, you find the world unrecognisable. The horizon is in a different place. The sun has changed colour. Nothing remains of the terrain you know. As for you, you are alive. But it's not the same as living. It's no wonder the survivors of such disasters so often wish they had perished with others. " — p. 206 Reception One week after publication, the novel became No. 1 on The New York Times Best Seller list in 2006. Reviews