In his book Metamorphoses of Science Fiction (1979), Suvin introduced a number of ideas that remain central in sf criticism: cognitive estrangement, the novum and sf's genetic link with utopia. In the notion of cognitive estrangement, Suvin conflate two distict, but related, ideas of estrangement from earlier literary theory: ostranenie (de-familiarization) from the Russian Formalists, and Berthold Brecht's Verfremdungseffekt (alienation effect). […] Even more influential in sf theory than cognitive estrangement is Suvin's concept of the novum.