A chiasm is a literary structure where vocabulary of the first section of a passage is repeated in reverse order in the second. The center of the chiasm is typically the climax of the passage. In Luke 4:21-30 the center and climax is Jesus pointing out that there were many widows in Israel in the day of Elijah, but God sent Elijah only to a Gentile woman and that there were also many lepers in Israel but God sent Elijah to a Syrian leper (Luke 4:25-27).