The Gaia hypothesis, first put forth in the mid-1960s, and published in book form in 1975, has had a radical effect on scientific views of evolution and the environment. Fiercely debated by biologists, chemists, and cyberneticists, it has been the subject of numerous conferences and a BBC special which aired on public TV's "Nova" series. Green Peace and other environmental groups have embraced the theory, and Isaac Asimov incorporated it into two his science fiction novels. Now, James Lovelock provides a new preface to his his seminal work, confronting his critics, and, addressing the current advances in science and technology, demonstrates how his predictions have already begun to be fulfilled. According to the Gaia hypothesis, the environment does not coincidentally support life on earth; rather the two interact much the way a bird and its nest interact. "The Earth's living matter," writes Lovelock, "air, oceans, and land surface form a complex system which can be seen as a single organism and which has the capacity to keep our planet a fit place for life." This revolutionary book offers the clearest explanation of the interaction of life and the environment.