Animal fables pass from country to country and century to century, but not unchanged. Because fables have explicit moralizations, the innovative medieval fabulists (Marie, Odo, and Berechiah through Henryson) help us test what authors meant by meaning and what freedoms they took with tradition. We catch them thinking aloud. As they develop social satire, play with allegory, and dramatize style, they maintain a consistent reasoning process something like what we now call structuralist, but something, too, like Augustinian exegesis. We can partially learn to read like a medieval reader, yet we find even the explicit and documented meanings too various to be caught, caged, and cataloged by our theories. With fables as with their wilder cousins, the Nun's Priest's Tale, the Bestiary of Love, and unmoralized literature, neither we nor the medieval reader can anticipate when the author will double back to surprise us. Surprise, it seems, was itself a tradition.