[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, and most other writers would have taken it elsewhere. By choosing as he has, Leiber scorns some easy crowd-pleasing effects in order to test the boundaries of science fiction and gothic horror as they apply to modern life. In this he is foregoing the traditions of both fields and attempting something new, exciting, and quite valuable. Leiber writes in the tradition of the English, French and German gothic writers of the early 19th century who reacted to their revolutionary age by acknowledging the vastness of human ignorance. But Leiber also stands with the early optimistic science fiction writers, with Jules Verne and H. G. Wells, because of his faith in man's innate ability to adapt and equip himself for the future whatever it may hold. In this conjunction of praise and dispraise he follows only one gothic writer of real power, Mary Shelley. He simultaneously challenges the dark fearful past and the uncertain but possibly bright future. (p. viii)
It is no coincidence that Leiber chooses the early 20th century, instead of any other historical or future era, as the Greenwich Standard Time of the Changewar. The 20th century is like no other for complexity and confusion on a worldwide scale—or within the individual mind. The Changewar is a rationalizing metaphor for the inexplicable in modern life, a fantastic model for an even more fantastical universe in which nothing is just exactly as it appears…. We are all part of the Changewar in our secret fear that our private worlds will come tumbling down around us.
This personal horror is the source of many of Leiber's best fictions. It is at its most intense and provocative when he deals with modern, particularly urban life…. This is the fabric of a modern peculiarly urban gothic mode—a transformation of a traditional horror form to the 20th century cityscape—a transformation that takes its most complete and satisfying shape in the Changewar saga.
The Changewar stories proved to be particularly apt vehicles for the reworking of old forms. Their basic premise is the theory of change, a theory which Leiber has equipped with a science-fictional apparatus as fascinating and telling as Isaac Asimov's Laws of Robotics. The basic theme of these stories is the consequences of change, particularly on the individual. Leiber seems to be telling us that we cannot live in an increasingly complex and manifold world without feeling some ill effects. His Changewar stories emphasize the complected nature of modern life by mixing science fiction with gothically conceived descriptive elements (his spiders and snakes, wolves and ghosts) thereby attempting to reconcile technology with the supernatural mind with matter in the modern world. (pp. ix-x)
Robert Thurston in his introduction to … The Big Time [see excerpt above], makes a good case for theatre as a device and metaphor in Leiber's fictions. With Leiber's theatrical and film background it comes as no surprise that he is adept at setting a stage and bringing players to life. Leiber's stories are in a very real sense psychological dramas, the action taking place in the character's minds. The settings, the science-fictional and gothic props, serve the same staging purpose as, say, Yorick's skull—a point of departure for the real meat of the story, an individual's self-discovery. (pp. x-xi)
[Leiber's] is a fiction of paradoxes if not opposites. Good and evil, ignorance and knowledge, inside and outside, praise and dispraise, past and future: all play their part in Leiber's world. Science fiction and gothic horror, too, are opposites which Leiber has successfully wedded in the Changewar saga in order to better probe the scienti-supernaturalism of modern life. Fritz Leiber is one of the first to make this connection between the dark recesses of man's psyche and the swiftly eddying future. (p. xvi)
John Silbersack, "Introduction" (copyright © 1978 by John Silbersack; reprinted by permission of the author), in The Change War by Fritz Leiber, Gregg Press, 1978, pp. vii-xvi.