Book excerpt: The origins of life remains one of the great unsolved mysteries of science. Growing evidence suggests that the first organisms lived deep underground, in environments previously thought to be uninhabitable, and that microbes carried inside rocks have travelled between Earth and Mars. But the question remains: how can life spring into being from non-living chemicals? THE FIFTH MIRACLE reveals the remarkable new theories and discoveries that seem set to transform our understanding of life's role in the unfolding drama of the cosmos.