Richard Kieckhefer discusses the Franklin's use of magic in the context of magic in romance narratives, noting that when Aurelius makes the rocks disappear--which they do, at least as far as Dorigen is concerned--nobody bothers to verify the deed. It is enough for Aurelius to say that it has been done for Dorigen to be plunged into despair.
Another and earlier episode of magic in the tale is the scene conjured by the magician in Orleans, a young clerk who recognizes Aurelius and his brother (V.1175) and their reason for coming before they have a chance to explain--an episode that recalls the moment in the Pardoner's Tale when the old man suddenly appears to the three men as if out of nowhere and confronts them. The young magician shows his visitors "parkes ful of wilde deer," great deer slain by hounds, and other bloody hunting scenes; and then--furthering the aristocratic context--they see visions of knights jousting and even Dorigen dancing ("his lady on a daunce" V.1199). The magician claps his hands and the visions disappear.
Note the great care Chaucer uses to set up the qualifications of the magician who comes with Aurelius. The Franklin says that he "kan no termes of astrologye" (V.1266) for example, and other preparations are equally elaborate.
Among the directions you could work in this area are these:
What was Chaucer's knowledge of magic? What were his sources for the magical lore in this text? You can begin with the notes to the Riverside Chaucer.
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