Theon defines fable as “a fictional story which images the truth (Μῦθός ἐστι λόγος ψευδὴς εἰκονίζων ἀλήθειαν).” The definition is fairly simple, but like the chreia, the fable can be expanded or contracted, inflected, confirmed, refuted, and woven into a narrative.
Given this basic definition of the exercise of fable, it seems to me that the parables of Jesus fit nicely into this category. If that is the case, then perhaps we can find insight into the composition of such stories from the progymnasmata.
A couple of notes. First, one of the things that you can do with a fable is inflect your main subject in varying cases. I have given an example of this here as I discussed the Parable of the Prodigal Son. In that parable, the term father is inflected in all five cases, clearly distinguishing the father as the focus of the parable.
Another interesting aspect of this preliminary exercise is the practice of adding a summary statement that sums up the theme of the parable. Theon writes,
"It is possible to provide a conclusion whenever, after the fable has been stated, we venture to bring in some gnomic statement fitting it... There can be several conclusions (epilogoi) for one fable when we take a start from the contents of the fable, and conversely one conclusion when many fables reflect it." (Theon, 75, Kennedy).Several of Jesus' parables get such a concluding "gnomic" statement or maxim. An interesting example would be the parable of the unjust steward in Luke 16. After the parable, Jesus rattles off several maxims that capture the theme of the parable. Jesus says:
And I tell you, make friends for yourselves by means of dishonest wealth so that when it is gone, they may welcome you into the eternal homes.
Whoever is faithful in a very little is faithful also in much; and whoever is dishonest in a very little is dishonest also in much.
If then you have not been faithful with the dishonest wealth, who will entrust to you the true riches?
And if you have not been faithful with what belongs to another, who will give you what is your own?
No slave can serve two masters; for a slave will either hate the one and love the other, or be devoted to the one and despise the other.
You cannot serve God and wealth.All six of these gnomic sayings are used to summarize and interpret the parable of the unjust steward. The most interesting of these comments to me are the last two. All of the rest of the comments are found in Luke alone. The last two about serving two masters is a parallel with Matthew and the wording is nearly verbatim. Now, depending on which source theory you are working with, Luke has taken this saying either from Q or from Matthew and placed it with his special L material in this place. Which of these options makes the most sense?