Science fiction is a modern genre. Though writers in antiquity sometimes dealt with themes common to modern science fiction, their stories made no attempt at scientific and technological plausibility, the feature that distinguishes science fiction from earlier speculative writings and other contemporary speculative genres such as fantasy and horror. The genre formally emerged in the West, where the social transformations wrought by the Industrial Revolution first led writers and intellectuals to extrapolate the future impact of technology. By the beginning of the 20th century, an array of standard science fiction “sets” had developed around certain themes, among them space travel, robots, alien beings, and time travel (see below Major science fiction themes). The customary “theatrics” of science fiction include prophetic warnings, utopian aspirations, elaborate scenarios for entirely imaginary worlds, titanic disasters, strange voyages, and political agitation of many extremist flavours, presented in the form of sermons, meditations, satires, allegories, and parodies—exhibiting every conceivable attitude toward the process of techno-social change, from cynical despair to cosmic bliss. Science fiction writers often seek out new scientific and technical developments in order to prognosticate freely the techno-social changes that will shock the readers’ sense of cultural propriety and expand their consciousness. This approach was central to the work of H.G. Wells, a founder of the genre and likely its greatest writer. Wells was an ardent student of the 19th-century British scientist T.H. Huxley, whose vociferous championing of Charles Darwin’s theory of evolution earned him the epithet “Darwin’s Bulldog.” Wells’s literary career gives ample evidence of science fiction’s latent radicalism, its affinity for aggressive satire and utopian political agendas, as well as its dire predictions of technological destruction. This dark dystopian side can be seen especially in the work of T.H. Huxley’s grandson, Aldous Huxley, who was a social satirist, an advocate of psychedelic drugs, and the author of a dystopian classic, Brave New World (1932). The sense of dread was also cultivated by H.P. Lovecraft, who invented the famous Necronomicon, an imaginary book of knowledge so ferocious that any scientist who dares to read it succumbs to madness. On a more personal level, the works of Philip K. Dick (often adapted for film) present metaphysical conundrums about identity, humanity, and the nature of reality. Perhaps bleakest of all, the English philosopher Olaf Stapledon’s mind-stretching novels picture all of human history as a frail, passing bubble in the cold galactic stream of space and time.