Why does the Wife of Bath ramble through such an extensive prologue? 

Chaucer presents an image of a strong willed, free-thinking woman who would live by her own accord. She defies the prevailing thought of her time and gives her own interpretation of scripture (lines 77-145) she speaks freely of Ovid, and Ptholomy and rips the pages from her fifth husbands book.  Chaucer seems to glaringly protrude from this portrait of the lady and his voice seems to be heard over hers throughout the prologue. But I put that aside, for what I know of Chaucer's intent is before me on the page. Chaucer presents a woman of thought and insight. So what do we make of the tale that she tells? What does he mean to illuminate with the story of an errant knight that defiles a maid and must search for an eternal truth? Is Chaucer mocking marriage as is done in the Romance of the Rose?