The fictional worlds of Philip K. Dick are populated by strange creatures and situations: men with enormous steel teeth, private detectives who own electric animals, self-governing insane asylums. It is from these bizarre places that Dick allows himself to explore the rocky terrain of reality and illusion. His characters are chiefly in charge of this task. "All of his work," Charles Platt wrote in Dream Makers: The Uncommon People Who Write Science Fiction, "starts with the basic assumption that there cannot be one, single, objective reality. Everything is a matter of perception. The ground is liable to shift under your feet. A protagonist may find himself living out another person's dream, or he may enter a drug- induced state that actually makes better sense than the real world, or he may cross into a different universe completely." With inspired plots and exciting worlds to explore, readers have made...