The alternate history device is not used by Dick as often as the other elements in the science fiction repertoire. Time travel is much more popular, and in a sense alternative history is time travel. Most science fiction readers would be familiar with Murray Leinster's influential story "Sidewise in Time" (1932), but not with the book which seems to have influenced The Man in the High Castle the most: the I Ching, or Book of Changes (12th century B.C.) Dick actually used this book of divination or Taoist oracle to compose his novel. He consulted it on every major decision he made in writing the novel. Also, it figures prominently in The Man in the High Castle itself. All of the major characters read and try to conduct their lives by it. And, as a final twist, the I Ching is the book which the man...