"What is beyond nature drives the audience not to persuasion but to ecstacy. What is wonderful, with its stunning power, prevails everywhere over that which aims merely at persuasion and at gracefulness."-- Longinus, Part I, ON THE SUBLIME, trs. Arieti and Crossett.
"This seemingly simple opposition and prioritization is an index of a broad shift away from a classical world-view: whereas Aristotle actually prescribed necessity and probability, universality and typicality; as the bases for poetry's engagement with the world, Longinus advocates precisely what deviates from such universality. It is an aesthetic premised not on what is central to human experience but precisely on what escapes such centrality..."-- M.A.R. Habib, A HISTORY OF LITERARY CRITICISM AND THEORY, p. 125.
In addition to Professor Habib's perspicacious pronouncement on Longinus (circa anywhere from 1 to 3 A.D.), I would add that in a sense Longinus is also a distant literary ancestor to any critic attempting to understand art through a comprehension of its symbolic nature, as opposed to whatever overt discourse the work may offer (or seem to offer).
To be sure, Longinus' influence was nowhere near as prevalent as that of Aristotle, with the result that the formative years of literary criticism were much more devoted to (bringing in my Langerian terms again here) the "discursive" rather than the "presentational." Longinus did see some revival by Europeans during both the Enlightenment and Romantic eras, and though many of his views are clearly conditioned by the Greco-Roman culture he shared, his emphasis on poetry's ability to go "beyond nature" in its effects, rather than to simply persuade like your average rhetorician, was as Habib says an important step away from regarding art as primarily discursive in nature.
I won't get into the tangled matter of "the sublime," which would involve how the notion evolved through varied treatments by Addison, Burke, Kant and others. But in short Longinus' reasoning depends on certain concepts or images being able to induce a kind of "ecstacy" in those who identify with these symbolic representations, and with this piece of logic (which seems self-evident to me at very least) Longinus successfully opposes the notion that literature depends first and foremost on the "mimesis" of real life propounded by Aristotle.
Admittedly, Longinus is not dealing with signs and symbols after the same fashion as modern critics. Still, his insights prove useful for myth-criticism, to the extent that myth-criticism too tries to demonstrate that while all human-created literary signifiers may share equal origins in theory, in practice some are "equal-er" than others.
More on this in GESTURE AND GESTALT PART 5.