In the narrative sense of the term, a fable is a very brief invented, double-meaning story in which a lesson of every day practical morality is taught. The kind of lesson is one of the points that distinguish fable from parable and allegory. The fable never aims higher than inculcating maxims of prudential conduct--industry, caution, foresight, and the like--and these it will sometimes recommend at the expense of the higher, self-forgetting virtues. A typical fable reaches just the pitch of morality which the world will approve. In spirit the fable is often humorous, often ironical. In diction it is always simple, forceful, and appropriate. Three classes of fables have been noticed: (1) the rational--in which the actors and speakers are solely human beings or the gods of mythology, (2) the non-rational--in which the heroes are solely animals, trees, vegetables, or inanimate objects, (3) the mixed--in which the rational and non-rational are combined. [Classes of fables] Now what distinguishes all these from myth and legend is the presence of the evident and acknowledged didactic purpose. What distinguishes the first class, the rational fable, from a parable is the low plane of the motive. Above the utilitarian the fable never rises. If the fable teaches honesty, it teaches it merely as the best policy. What distinguishes the non-rational and the mixed fables from allegory is both the limitation of the moral and the kind of hero. The lesson of the fable is always piquant, single, and clear. The actors in a fable are always things concrete in nature as well as in the story. The most popular, and hence the most typical of the three classes of fables, is the second, often called also the "beast fable." The beast fable departs somewhat from the laws of nature. In the dialogue, animals and inanimate objects act like human beings. A fox and a bear, for instance, will philosophize on politics. A lion and a mouse will exchange courtesies. But it is a remarkable feature of this type of story that we do not resent the incongruity. And that we do not resent it is because there is a truthfulness that is more interesting to us than is the natural order of the universe--namely, the truthfulness of characterization. Here the verisimilitude must be complete. Although acting the part of rational beings, the animals must be true to our accepted notion of their animal nature--a fox must be foxy; a bear, bearish; a lion, haughty; a mouse, timid; a cat, deceptive; a monkey, mischievous; a canary, dependent; an eagle, lofty; and so on, and so on. It is not necessary that they have no other characteristics, but it is necessary that they possess the commonly ascribed ones. [How to write an original fable]