Chiastic structure is a structure used most notably in the Torah. The structure is made up of concepts or ideas in an order ABC…CBA so that the first concept that comes up is also the last, the second is the second to last, and so on. Also, a chiastic structure can also be of the form ABBAABB…ABBA.
Why Chi?
Chi is a Greek letter that is shaped like an X. Chi is made up of two lines crossing each other, so the line that starts leftmost on top comes down and is rightmost on the bottom, and vice versa. If one thinks of the lines as concepts, one sees that concept A , which comes first, is also last, and concept B, which comes after A, comes before A. If one adds in more lines representing other concepts, one gets a chiastic structure with more concepts.
The ABC…CBA chiastic stucture
The ABC…CBA chiastic stucture is used in many places in the Torah. This kind of chiastic structure is used to give emphasis to the middle concept, i.e., the concept that appears either twice in succession or only appears once. Also, it shows that the other ideas are all leading up to the middle idea or concept. A notable example is the chiastic structure running from the middle of the Book of Exodus all the way through the end of the Book of Leviticus. The structure begins with the covenant made from God to the Jewish People at Mount Sinai, and ends with the Admonition from God to the Jews if they will not follow his laws, which is also a sort of covenant. The main ideas are in the middle of Leviticus, from chapter 11 through chapter 20. Those chapters deal with the holiness in the Tabernacle and the holiness of the Jewish homeland in general. The chiastic structure points us to the central idea, that of the holiness of the Jewish people in what they do. It tells us that if the Jews keep the covenant and all the laws around the central concept, they will be rewarded with a sense of holiness in their Tabernacle and in their land in general.
The ABBAABB…ABBA chiastic structure
The ABBABB…ABBA chiastic structure is used to tell the reader to contrast concepts A and B, which are usually closely related, but very different. The format shows the contrast between the two ideas, and tells the reader to look deeper. An example of this is in the beginning of chapter 4 of the Book of Genesis, when the two sons of Adam, Cain and Abel, are contrasted. The Torah tells us about their names, their occupations, and their offerings. The Torah mentions Cain first, then Abel twice, then Cain twice, and so on. The structure draws attention to the differences between Cain and Abel, pointing out the essential difference in their personalities.
See Also
Main Article Chi (letter)