The most likely reason "The Monk's Tale" is full of parables is that parables were commonplace in Chaucer's time, and audiences would have found them familiar.
A parable is a short story, in prose or verse,which purpose is to teach a lesson or principle to the audience. It differs from a fable since fables talk about animals, plants and other nonhuman objects, whereas parables usually have humans as characters. Parables are often associated with Jesus Christ, hence, these are common in religious teachings. This is why Chaucer associates the monk with parables.
