At the beginning of the book, the girls discuss the butterfly effect—a chaos theory that argues minor changes can have big effects. Sam’s efforts throughout the book are all examples of this theory. She changes small things such as sending Juliet a large bouquet of roses, and the effects lead to major differences from the original course, and sometimes from the intended course. Butterflies are also symbolic of transformation, because they start as caterpillars which then build a cocoon to change into a butterfly. This relates to the theme of redemption, and therefore can apply to any of the dynamic characters of this story, especially Sam.