The plot has been related to invasion literature of the time. The novel has been variously interpreted as a commentary on evolutionary theory, British Imperialism, and generally Victorian superstitions, fears and prejudices. At the time of publication it was classified as a scientific romance, like his earlier novel The Time Machine. The War of the Worlds has been both popular (having never gone out of print) and influential, spawning half a dozen feature films, radio dramas, a record album, various comic book adaptations, a television series, and sequels or parallel stories by other authors. It has even influenced the work of scientists, notably Robert Hutchings Goddard.