I first found this quote on my AP Language exam and remember it every few years, so I now post it here.  This is my favorite exposition on the nature of literature:

“Consider a prosaic, quite unambiguous statement like the one sometimes seen in the London Underground system: ‘Dogs must be carried on the escalator.’  This is not perhaps quite as unambiguous as it seems at first sight: does it mean that you must carry a dog on the escalator?  Are you likely to be banned from the escalator unless you can find some stray mongrel to clutch in your arms on the way up?  Many apparently straightforward notices contain such ambiguities: ‘Refuse to be put in this basket,’ for instance, or the British road-sign ‘Way Out’ as read by a Californian. But even leaving such troubling ambiguities aside, it is surely obvious that the underground notice could be read as literature.  One could let oneself be arrested by the abrupt, minatory staccato of the first ponderous monosyllables; find one’s mind drifting, by the time it had reached the rich allusiveness of ‘carried’, to suggestive resonances of helping lame dogs through life; and perhaps even detect in the very lilt and inflection of the word ‘escalator’ a miming of the rolling, up-and-down motion of the thing itself.  This may well be a fruitless sort of pursuit, but…it at least has the advantage of suggesting that ‘literature’ may be at least as much a question of what people to do writing as what writing does to them.”

-Terry Eagleton

“Literary Theory: An Introduction.”  Minneapolis: University of Minnesota Press, 2008.