What is a chiasm?

In the Bible, a chiasm (also known as chiasmus, from the Greek letter X, pronounced “kai”) is a literary device where ideas or phrases are presented & then repeated or inverted in a mirror-like, symmetrical structure. It's like a backward echo, emphasizing key themes & ideas by repeating them in reverse order. This structure can be found at different levels, from single verses to entire chapters or even books. In the middle of a chiastic structure is the point of the arrow, the unifying center to which the first half builds and from which the second half flows.