Chiasmus is an inverted-parallel literary form that was employed by ancient Hebrew biblical writers, among others. An instance of this form, called a “chiasm,” presents two or more literary elements, and then restates them in reverse order. Short chiasms are not uncommon in literature. In some cases, the authors undoubtedly intended to use that form for literary effect (that is, by design); in other cases, the elements fell into that form without author intent (that is, by chance). In 1969, John W. Welch reported his discovery of many-element chiasms in the Book of Mormon,1 which Joseph Smith testified to have translated from plates written anciently by Hebrew descendants.
“Does chiasmus appear in the Book of Mormon by chance?,” B. F. Edwards and W. F. Edwards, BYU Studies 43, no. 2, 103 (2004); http://byustudies.byu.edu/chiasmus/ .