Postmodernism rejects the central tenets of modernism, namely that knowledge is certain and objective. It is skeptical of grand narratives and universal truths, instead focusing on relative and local interpretations. Postmodernism celebrates difference and rejects rationality and science. In literature, postmodern works employ techniques like pastiche, parody, intertextuality and self-reflexivity. They question notions of reality, genre and the separation between high and low art. While postmodernism dominated from the late 20th century, more recent trends suggest a partial return to sincerity and meaning in a movement called post-postmodernism or new sincerity.