Since Josh mentioned Robbe-Grillet's essay "From Realism to Reality" in the comments yesterday, I'll share a few deadly passages from that essay:
"The discovery of reality will continue only if we abandon outworn forms."
"The style of the novel does not seek to inform, as does the chronicle, the testimony offered in evidence, or the scientific report, it constitutes reality. It never knows what it is seeking, it is ignorant of what it has to say; it is invention, invention of the world and of man, constant invention and perpetual interrogation."
"[In response to the oft cited idiocy "deep down nothing ever changes" and "there is nothing new under the sun"] ...in truth everything is constantly changing and there is always something new."
If you're interested in the question of realism, check out Roman Jakobson's essay "On Realism and Art" (1921), which you can read for free, here, via Dalkey Archive's journal Context.
If you're interested in the avant-garde, check out Clement Greenberg's essay "Avant-Garde and Kitsch" (1939), for free here.
Don't forget Walter Benjamin's "The Work of Art in the Age of Mechanical Reproduction" (1936), for free here.