Telepathy, reincarnation, voodoo, and witchcraft are just a few examples of phenomena now defined as paranormal activity. But just because these marvels lie beyond the reach of current scientific explanation does not mean that future developments will not bring understanding. For instance, some scientists now believe that the mysterious symptoms, such as hallucinations and spasms, of the accused witches in Salem may actually have been reactions to a type of poison. And a hundred years ago, who would have thought that acupuncture could be scientifically explained, let alone covered by most...