This book is fantasy/sci-fi for the ecologist or environmentalist. Its underlying theme is the need for knowledge and balance, and the great care that must be taken when tampering with worlds and peoples. While Gehn, Atrus' father, sees his role in opening up or creating worlds from an entirely exploitative perspective, Atrus recognizes the need for care, understanding and stewardship, and these contradictory goals become the central conflict of the plot. Those with a background in science will find Atrus' search for an understanding of the D'ni characters, which are the ultimate causes of the characteristics of each world, particularly resonant, and will understand his continual surprise when their results are often not exactly what he anticipates. The connections inherent in each world cause small changes to have indirect and unexpected effects, and his struggles to understand the structure of his worlds are much like those of an ecologist, the only difference being that he can manipulate the rules through writing. However, in case I have made this novel somehow seem too cerebral, I would like to conclude by saying simply that I think this could be an enjoyable read for anyone, particulary those who like fantasy, or who enjoy being brought into strange and fascinating worlds through engaging language.