The multilevel nature of research in literary studies sheds some light on the possibility of formulating a single, general theory of literature. In the tradition that ranges from Saussurean linguistics, through formalism, structuralism, to post-structuralism, it was commonly assumed that linguistics can provide us with an adequate paradigm for literary studies. In the recent decades, there has been a tremendous change in how we understand the role of metaphors. Metaphor has always been an important part of research into linguistics, literature, rhetoric or philosophy of language. One popular theory of emotions within cognitive framework is the appraisal theory. Emotional triggers might be more direct and immediate, as people all know, since they are all capable of recognizing the feelings of others and responding to or sharing their emotional concerns without being involved in any actual plan. Hogan defines literary universals as "properties and relations found across a range of literary traditions".