Vladimir Nabokov's novel, Ada or Ardor: A Family Chronicle (1969), is a story of incest that takes place within an alternate North America settled in part by Czarist Russia and that borrows from Dick's idea of "alternate-alternate" history (the world of Nabokov's hero is wracked by rumors of a "counter-earth" that apparently is ours). Some critics believe that the references to a counter-earth suggest that the world portrayed in Ada is a delusion in the mind of the hero (another favorite theme of Dick's novels). Strikingly, the characters in Ada seem to acknowledge their own world as the copy or negative version, calling it "Anti-Terra", while its mythical twin is the real "Terra". Like history, science has followed a divergent path on Anti-Terra: it boasts all the same technology as our world, but all based on water instead of electricity; e.g., when a character in Ada makes a long-distance call, all the toilets in the house flush at once to provide hydraulic power.
