In his first book, The End of Nature, Bill McKibben demonstrated that humanity had begun to irrevocably alter
and endanger our environment on a global scale. Now he turns his eye to an array of technologies that could change
our relationships, not just with the rest of nature but with ourselves. As he explores the frontiers of genetic
engineering, robotics, and nanotechnology -- all of which we are approaching with astonishing speed -- he shows
that each threatens to take us to a point of no return. We now stand, in Michael Pollan's words, "on a moral
and existential threshold -- or cliff." McKibben offers a celebration of what it means to be human and a warning
that we risk the loss of all meaning if we step across that threshold. Acclaimed for its passion and insight, this
wise and eloquent book argues that we cannot grow forever in reach and power -- that we must at last learn how
to say, "Enough."