THEME
The theme of this book is moving on to the future because Colin needed to move on from Katherine XIX and from his old ways of doing things. When Colin and Lindsey got together, Colin tried to create an equation based on past relationships, he predicted that Lindsey would break it off in four days. After four days, he found that his theory, which he has had with most of the nineteen Katherines, didn't hold true with Lindsey, he finally realizes that he can't use a science equation to figure out his love life.