Medieval comedy more often than not strikes modern sensibilities as drastic. And if life was indeed harsher and more brutish then, as we suppose, maybe people laughed more viciously. Ridiculous antics were routinely used to drive hard moral lessons, as in this scalding attack on corruption in monastic orders. What may seem an incongruous confusion of attitudes comes a little clearer when we see the devout lady and her husband in this story not just as murderous pranksters but God's agents of retribution.
Still, there is no way to heal our surprise at the zest with which church and clergy were attacked and abused (boiled alive, even), saturated though medieval life was with religion and piety. We have to accept a theory of realism that remained throughout the Middle ages the cornerstone of all serious thought: the distinction separating the particular from the general and assigning reality only to the latter. Church, priesthood, holy orders, and all that went with them were vital, as abstractions, as manifestations of divine order, even though a church, a clergyman, or a monk, as a particular specimen, might be just as vile as anything else on earth. As long as medieval attitudes prevailed, even massive corruption in the church failed to damage the sanctity of what the church stood for. A student, however, with nothing to sanctify him but the eternally wrangling university of theologians and philosophers, was another matter, beyond any apology.
The textual history of this story is exceedingly complex, involving a multitude of diversions and analogues, reaching back into ancient Oriental literature.* Our German author, not himself an Alsatian, turned his wit against the friars and drunkard scholars of Colmar (which isn't on the Rhein), where monastic foundations flourished in the latter part of the thirteenth century.
*Maybe a ghost of it survives in the fairy tales, where the wicked wolf is prone to land in a boiling vat. An Old French version is translated in Medieval Comic Tales, ed. Peter Rickard (Rowman and Littlefield, 1973), 4-7.