In his essay “Tradition and the Individual Talent,” T.S. Eliot separates the wheat from the chaff, the great work of art from the lesser.
…No poet, no artist of any art, has his complete meaning alone. His significance, his appreciation is the appreciation of his relation to the dead poets and artists. You cannot value him alone; you must set him, for contrast and comparison, among the dead. I mean this as a principle of æsthetic, not merely historical, criticism. The necessity that he shall conform, that he shall cohere, is not one-sided; what happens when a new work of art is created is something that happens simultaneously to all the works of art which preceded it. The existing monuments form an ideal order among themselves, which is modified by the introduction of the new (the really new) work of art among them…
… If you compare several representative passages of the greatest poetry you see how great is the variety of types of combination, and also how completely any semi-ethical criterion of “sublimity” misses the mark. For it is not the “greatness,” the intensity, of the emotions, the components, but the intensity of the artistic process, the pressure, so to speak, under which the fusion takes place, that counts…
Much more here.
One of the best essays ever penned! If you haven't already, read his Four Quartets (free online) and Murder in the Cathedral (play abt Thomas a Becket).