A future of designer humans, smart machines, protean technology. Our dwindled descendents exiled to large space stations visit Cleansed Earth occasionally for gravity- and sensory-deprivation therapy. Human longevity, at last attained, ironically creates a Great Plague of Suicidal Despair, Disnovelling, born of the intruding longer prospect of bloody Nature and of the impersonal hurtling cosmic vastitudes. Centwen, a resurrected twentieth century archetype joined by elites and archetypes from other centuries, learns from his tour guides, the superbot, Prodigy, and its human creator, Great...