The question of how poetry might be described and defined as a linguistic structure has troubled readers since…well, since we have been able to keep records of what critics have said about literature. Regarding English poetry, this quest can be divided roughly into three stages: the classical sources (Aristotle, Plato, Longinus, etc.); the sixteenth-nineteenth centuries, in which critics both drew upon classical precedent and developed theories to account for the types, methods and objectives of modern English poetry; and the twentieth century, in which literary criticism has become an academic discipline and has found itself encountering, sometimes harmoniously and sometimes not, the non-literary practices of historicism, semiotics, sociology, politics and, most significantly, linguistics.
Apart from sharing the objective of defining poetry, the critics of these periods have one other, more paradoxical, thing in common. They already know what in purely abstract terms poetry is, but they remain uncertain about what exactly it does to and for the reader, precisely how these effects are achieved and to what extent such effects can be identified as purely poetic, rather than as elements drawn from the signifying procedures of other linguistic discourses. I can tell you in crude but accurate terms how to recognise a poem: it is a structure whose formal common denominator-that which separates it from non-poetic discourse-is its division into lines. The title of that rare and briefly fashionable phenomenon, the prose poem, testifies to the validity of my definition-the text calls itself a prose poem in order to warn the reader of its claims to be something that in basic empirical and formal terms it is not. The problem, or the paradox, faces us when we attempt to state how,