[In A Swiftly Tilting Planet, the] author picks up themes from earlier books—time as a relative phenomenon, the interdependency of people and events, the importance of the individual—and presents them in an unusual framework. She considers the possibility of one person's altering the course of history by traveling back in time and entering the consciousness of other individuals: "What happens in one time can make a difference in what happens in another time, far more than we realize…. Nothing, no one, is too small to matter."… On one level the book takes place in the course of an evening; on another it spans centuries. Unfortunately, the different episodes are not well integrated, and the author's tendency to philosophize interrupts the smooth flow of the narrative. Characterization, though, is carefully handled, and if the book is flawed on a structural level, it is impeccable on an emotional...