Brooks and Warren were teaching using textbooks "full of biographical facts and impressionistic criticism" (Singh 1991). The textbooks failed to show how poetic language differed from the language of an editorial or a work of non-fiction. From this frustration, Brooks and Warren published "Understanding Poetry". In the book, the authors assert poetry should be taught as poetry, and the critic should resist reducing a poem to a simple paraphrase, explicating it through biographical or historical contexts, and interpreting it didactically (Singh 1991). For Brooks and Warren, paraphrase and biographical and historical background information is useful as a means of clarifying interpretation, but it should be used as means to an end (Singh 1991).