At the level of the passage, chiasmus is clearly a rhetorical figure, which may or may not be ornamental (see Nanny, "Chiasmus in Literature: Ornament or Function?," in Word and Image 4.1 (1988): 51-59). At the level of the passage,viewing structures as chiastic may depend on literal arrangement, symbolic arrangement (in the sense of narrative "balance"), or a combination of both. At any rate, when considered in any sense beyond the literal figure, chiasmus can be a useful structure for describing relations of balance, especially those involving inversion (see Arteaga, "Tricks of GenderXing," _Stanford Humanities Review_ 3.1 (1993): 112-26). See Lanham, _A Handlist of Rhetorical Terms_, 2E (Berkeley: U of CA P,: 33-34; see also Antimetabole and Commutatio in the same volume;
Quinn, in _Figures of Speech: 60 Ways to Turn a Phrase_ (Layton, UT:Peregrine Smith, 1982): 95, 102, links chiasmus to epanados, with chiasmus "at the level of passage"; epanados is a sentence organized "spatially around a center." Quinn cites Num. 15: 35 and John 5:8 as examples of chiastic formulations, and adds that Abraham's story in Genesis, Ruth, Hamlet, and The Tempest, Tartuffe, and The Iliad, are all organized chiastically; Quinn also claims for chiasmus a relation to the palindrome, but, while I personally see this as an obvious connection, it is not universally accepted;
In Hawthorne, _A Glossary of Literary Theory_ (NY: Edward Arnold, 1992): chiasmus is illustrated through the familiar example of the last sentence of Joyce's "The Dead," a passage in which the structural symmetry of the sentence recalls the structural symmetry of the story and of the entire cycle of stories; Norrman, in _The Insecure World of Henry James's Fiction: Intensity and Ambiguity_ (London: Macmillan, 1982) and _Samuel Butler and the Meaning of Chiasmus_ (London: Macmillan, 1986), reads chiastic structures as keys to understanding the fiction of these two authors and also the authors themselves;
For two examples of plain-language use of chiasmus in a sentence of criticism, _Public Access: Literary Theory and American Cultural Politics_ (NY: Verso, 1994): 80; and Montrose, "Professing the Renaissance:the Poetics and Politics of Culture," in Veeser, ed. _The New Historicism_(NY: Routledge, 1989): The post-structuralist orientation to history now emerging in literary studies may be characterized chiastically, as a reciprocal concern with the historicity of texts and the textuality of history.
Finally, who but Doctor Johnson would provide a chiasmus useful for both meditation on the figure and for figurations of scholarship itself: Your manuscript is both good and original; but the part that is good is not original, and the part that is original is not good. (Lanham, _Handlist_= 33).