[The Change War] stories reflect Leiber's fascination with the instability of much of modern American life. In Leiber's best fictions he is able to endow this instability, this American capacity for change, with a profound supernaturalism that can turn the most freakish accidents of urban chance into nightmares of paranoic intensity.

The Changewar plots are created around the premise that there are two forces in the universe battling for supremacy in the greatest war ever—a war conducted in all places and over all time. The war's object is to alter the course of past and present history in favor of one or the other of the two forces, known as Snakes or Spiders. At the end of time one side will have ultimately won by actually channeling history to its advantage. (pp. vii-viii)

The Changewar is an exercise in thought that can be carried in many directions...