A concept derived by Darko Suvin from Russian Formalism’s notion of ostranenie and Brecht, Bertolt’s closely related (but Marxism inflected) notion of the estrangement-effect in his Metamorphoses of Science Fiction (1979), a structuralism attempt to distinguish the genre of science fiction writing from other forms of fiction. As Jameson, Fredric points out in Archaeologies of the Future (2005), this is a rather exclusive definition, which emphasizes the rational scientific dimension of science fiction and rigorously excludes the kinds of flights of fancy associated with fantasy fiction. For Suvin, the key to cognitive estrangement is the presence in a story or novel of what he calls a ‘novum’, that is a device or machine that is absolutely new and whose presence compels us to imagine a different way of conceiving our world.