At the onset of "Life, Liberty and the Defense of Dignity," Leon Kass gives us a status report on where we stand today: "Human nature itself lies on the operating table, ready for alteration, for eugenic and psychic ''enhancement,'' for wholesale redesign. In leading laboratories, academic and industrial, new creators are confidently amassing their powers and quietly honing their skills, while on the street their evangelists are zealously prophesying a posthuman future. For anyone who cares about preserving our humanity, the time has come for paying attention." Trained as a medical doctor and biochemist, Dr. Kass has become one of our most provocative thinkers on bioethical issues. Now, in this brave and searching book, he also establishes himself as a prophetic voice summoning us to think deeply about the new biomedical technologies threatening to take us back to the future envisioned by Aldous Huxley in "Brave New World." As in Huxley''s dystopia, where life has been smoothed out by genetic manipulation, psychoactive drugs and high tech amusement, our own accelerating efforts to master reproduction and genetic endowment, to retard aging, and to conquer illness, imperfection, and death itself are animated by our most humane and progressive aspirations. But we are walking too quickly down the road to physical and psychological utopia, Kass believes, without pausing to assess the potential damage to our humanity from this brave new biology. In a series of meditations on cloning, embryo research, the human genome project, the sale of organs, and the assault on mortality itself, Kass evaluates the ongoing effort to break down the natural boundaries given us and to remake the human body into an instrument of our will. What does it mean to treat nascent human life as raw material to be exploited? What does it mean to blur the line between procreation and manufacture? What are the proper limits to this project for the remaking of human nature? These are the questions we should be asking to prevent runaway scientism with its utopian longings from reshaping humankind in the image of our own choosing. Kass believes that technology has done and will continue to do wonders for our health and longevity and that we have much to be thankful for. But there is more at stake in the biological revolution that saving life and avoiding death. We must also strive to protect the ideas and practices that give us dignity and keep us human. "Life, Liberty and the Defense of Dignity" challenges us to confront the posthuman future that may await us by thinking deeply about the life and death issues we face today.