[In "The Changeling" Snyder] writes about a pair of children who play in a grove of trees and invent a planet called the Land of Green Sky, where the Tree People could "glide like blowing leaves." At the end of the book, Green Sky is forgotten by the children because they grow up, but not by the author herself, who fortunately doesn't. For Zilpha Snyder the notion obviously developed on its own … until it became this book, "Below the Root," in which the once-playful Land of Green Sky is a world presented whole.

Of course the children's invention had to be broadened and surrounded with an ethical framework, until it resembled other alternate societies that exist in books, systems running back and forth in time, settings in which the physical or moral bravery of the characters reflects or is pitted against some good or evil imbedded in the...