A chiasm is a literary structure where themes 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 20:9-16 the center and climax is the parable pf the owner of a vineyard who sends first his slaves and then his son to obtain some of the produce but the vine-growers beat the slaves and kill the son (Luke 20:10-15).