The Parson's Tale is one of the longest of all the tales, and it seems even longer because of the tedious litany on abstract virtues and vices. Certainly, the Parson preaches with all the force that the medieval pulpit afforded him, and he ends with the compelling image of the goal of man's pilgrimage, that is, heaven and immortality.
The theology of the Middle Ages viewed this life as something of a cesspool that man was supposed to struggle through, committing as few sins as possible. This world was to be endured (never enjoyed) in order to achieve glory in the afterlife. Consequently, as the Parson says in his prologue, he would not tell a story simply to amuse or entertain, so instead, he offers a sermon. The intent of the sermon was didactic, to teach a lesson or give instructions on achieving immortality. For the medieval person, especially the rigorous theologians of the time, didactic intent is infinitely more important than artistic achievement. Thus, Chaucer ends the tales with this sermon, which is appropriately followed by his retraction of all of his earthly (worldly) works.
It is rather obvious from some of the tales told by the pilgrims, and particularly tales told by some of those connected with the ecclesiastical organization, that the church of Chaucer's time had fallen upon evil days. It is fitting, therefore, that the tales should end on the high moral tone of the Parson's sermon. This sermon can also function as a proper preparation for the visit to the Shrine of St. Thomas à Beckett, and finally, it seems to lead naturally to Chaucer's Retraction.
