Lyrical, almost rhapsodic paeans to Gala by one of James Lovelock's strongest supporters. Along with past collaborator Lynn Margulis, Sagan (Microcosmos, 1986, etc.--not reviewed) has done much to promote the hypothesis that Earth (""Gaia"") is a superorganism with self-regulatory powers. Over the eons, Gaia's activities have led to the elaboration of changes in the environment and the evolution of life forms. Now Sagan takes the concept a step farther with the notion that Earth is ready to expand to space. The vehicle will be biospheres--self-contained units that could be used to make planetary journeys, seed Mars, and so on. You've heard these ideas before in the various schemes of NASA scientists (as well as in science fiction). Sagan adds more: the schemes of an outfit called New Alchemy, various Russian designs, and even playful examples sold as educational toys in which tiny brine shrimp live for years in pint-sized closed aquaria in balance with algae and bacteria. But the rhapsody gets more and more mystical as Sagan ponders a human-technological symbiosis in which the borders between flesh, machine, and Earth disappear as we move toward cosmic consciousness. That movement will be fostered when we build biospheres on Earth that will enable us to get out of the dilemma that Lovelock aptly describes as ""cars, cattle, and chainsaws""--a neat shorthand for the air pollution, greenhouse effect, expensive meat economy, and chopping-down of forests that are creating ecological havoc. Unfortunately, the solution proposed cannot help but suggest a new elitism in which the haves can move into their mini-Galas in Earth or in space and leave the rest of us to pests and pollution.