A chiasm is a literary device in which a sequence of ideas is presented and then repeated in reverse order. The result is a “mirror” effect. Each idea is connected to its “reflection” in a related form.
Sometimes, there are four parts, with the fourth matching the fourth on the other side of the mirror, the third matching the third on the other side of the mirror, and so on. The purpose of a chiasm is to draw attention to the center and link parallel ideas.
The term chiasm comes from the Greek letter chi, which looks like our letter X, which is itself chiastic. Chiastic pattern is also called “ring structure.”
In poetry, chiasm is the repetition of any group of verse elements (including rhyme and grammatical structure) in reverse order, such as the rhyme scheme ABBA. An example of chiastic poetry is The Odyssey and the Iliad by Homer.
The Old and New Testaments are filled with chiastic patterns, including Genesis 3, Leviticus, parts of the Psalms, and the Gospel of Matthew.