How do we understand what literature means today having in mind that there are a number of great works (such as Homer's Iliad, or Don Quixote by Miguel de Cervantes, and Shakespeare's Hamlet) which we consider to be prime examples of literary art and the western canon, but, at the same time, that literature's essential properties are not indisputably established and have undergone critical changes throughout human history?
The margin between literary (novels, poems, plays) and non-literary (advertisements, news) texts is fairly well outlined but are there any texts which do not fit either of the two groups, or, to the contrary - which bear some essential characteristics of both groups and hence cannot be so easily categorized?