Mensa philosophica is a text generally attributed to Michael Scotus (c. 1175 - c. 1234) and sometimes to Theobaldus Anguilbertus, who actually wrote the preface. It was first printed in about 1480 at Cologne, and reprinted several times in the following decades.
A woman had confessed her sins and the priest took her behind the altar to administer the satisfaction through the so-called "lower discipline", i.e. whipping on the buttocks. Her husband, who had secretly followed her through jealousy, was moved to pity to think of the pain his wife would be subjected to, and stepped in, offering to receive the whipping in her place. The wife consented, admitting that her husband was better able to bear the punishment, and they swapped places. Just when the priest had begun the chastisement, the wife exclaimed: "Now then, holy father, lay on lustily: I am a great sinner."