In the most typical form some moral precept is set forth by means of a conception purely fantastic, and usually somewhat trivial into the bargain; there is something playful about it, that will not support a very exacting criticism, and the lesson must be apprehended by the fancy at half a hint.

Such is the great mass of the old stories of wise animals or foolish men that have amused our childhood.

But we should expect the fable, in company with other and more important literary forms, to be more and more loosely, or at least largely, comprehended as time went on, and so to degenerate in conception from this original type.

That depended for much of its piquancy on the very fact that it was fantastic: the point of the thing lay in a sort of humorous inappropriateness; and it is natural enough that pleasantry of this description should become less common, as men learn to suspect some serious analogy underneath.
Thus a comical story of an ape touches us quite differently after the proposition of Mr.Darwin's theory.

Moreover, there lay, perhaps, at the bottom of this primitive sort of fable, a humanity, a tenderness of rough truths; so that at the end of some story, in which vice or folly had met with its destined punishment, the fabulist might be able to assure his auditors, as we have often to assure tearful children on the like occasions, that they may dry their eyes, for none of it was true.
But this benefit of fiction becomes lost with more sophisticated hearers and authors: a man is no longer the dupe of his own artifice, and cannot deal playfully with truths that are a matter of bitter concern to him in his life.