In writing an original parable, one should avoid the diction of the Bible, that is, should avoid phraseology archaic or especially religious; but it would be well to imitate the simplicity and straightforwardness of the Biblical narrative. A modern parable writer to be successful would avoid mawkishness, and what is popularly designated as "preaching,"—but he would shadow forth nevertheless very clearly a high, spiritual truth. He would study living examples carefully so as to express inevitable actions in a few luminous words. There are many noble lessons to be taught by the actions of typical men in typical situations.
Working definition
The adjectives symbolic, serious, spiritual, typical, and natural might be embodied in a working definition thus: A parable is a narrative of imaginary events, a symbolic didactic story, wherein the actors are always types of men or types of men and animals (never exclusively of animals), and whereof the lesson is always spiritual, single, and separate, and the tone is always serious, and the events always appear natural and customary.
A list of proverbs that might be expanded into parables
1. God understands the dumb.
2. What a man acquires in his youth serves as a crutch in his old age.
3. Begin with small things that you may achieve great.
4. He who steals an egg will steal a horse also.
5. One can spoil the good name of a thousand.
6. One bad deed begets another.