What is the theme in The Demon-Haunted World by Carl Sagan?

Sience and superstition make up the major theme. Superstition, witchcraft, sky gods, and a belief in the supernatural are as old as humanity itself, according to Carl Sagan, and have continued into the modern world under the guise of the New Age. Science was basically invented by the ancient Greeks less than 2,000 years ago but has come into its full flowering only in the last few centuries. The succubi demons that purportedly seduced and abducted people in the Dark Ages have been replaced by little men with big eyes from outer space. Yet, the irrational beliefs that spring from fear and ignorance remain. Contemporary humans are presented with a duality: rational science or irrational beliefs and practices.