Dioneo begins his tale with an excuse for his off-color stories. Just as a black crow enhances the beauty of a flock of white doves by the contrast, his foolish tales augment the other narrators’ excellence. Today’s offering will highlight the contrast between his tales and theirs, so he begs more than the usual indulgence.
The fact that Dioneo is excusing his story before it begins suggests that it will be even more off-color than his previous offerings. However, he also makes a case for moderation and balance, claiming, in essence, that all things are acceptable in moderation. Since the rest of the tales are mostly sober, excellent, and within the bounds of moral propriety, Dioneo’s tales can’t threaten the balance of The Decameron generally. In addition, he claims that a little bit of nonsense and obscenity throws the virtues of the other tales into even starker relief.
In Barletta, a priest named Father Gianni di Barolo supplements his meager church income by small-time trading, carrying his wares to local fairs on his mare. He befriends another poor trader—whom he familiarly calls Neighbor Pietro—who carries his goods on a donkey. Whenever either man is in the other’s town, they stay together. But Pietro and his wife Gemmata have one little bed, so in Barletta, Gianni must sleep on a heap of straw in the stable.
The relationship between Father Gianni and Pietro is as even and reciprocal as possible. But Father Gianni is relatively better off since he has two revenue streams (trading and his church income), and he doesn’t have a wife to support. The slight imbalance in the hospitality the two men can show each other means that the priest must sleep in the stable instead of in the home.
When Father Gianni visits, Gemmata offers to stay with a friend so that he can share the bed with Neighbor Pietro. Father Gianni politely declines, saying that he’s comfortable in the stable. There, he has a magic ritual to turn his mare into a woman to sleep with. Gemmata is astonished at this thought, and she wants Pietro to learn the magic to turn her into a horse. That way, she can help him carry goods and make more money. Eventually, Father Gianni promises to show Pietro how it’s done—especially the hardest part, which is fastening on the tail. They will start before dawn the next day.
All the magic rituals invoked by the tales (with one notable exception in X, 9) are shams—Maso del Saggio’s magic stone made the gullible Calandrino look foolish (VIII, 3); Rinieri manipulated Elena into a vulnerable spot with a magic ritual (VIII, 7); and the magic scroll that helped Calandrino bring Niccolosa under his command was also just part of a larger prank (IX, 5). Thus, the idea of a magic ritual here foreshadows a trick about to be played. Given The Decameron’s heavy investment in anticlerical satire and critique of the clergy’s sexual hypocrisy, the audience is primed for something to happen between the priest and Gemmata. Gemmata’s investment in the magic ritual highlights the precarious state of poverty in which she and her husband live. Her insistence implies that her participation is an act of desperation.
Just before dawn, Neighbor Pietro and Gemmata summon Father Gianni—still in his nightshirt—to teach them. Extracting a promise that they will follow his instructions and never utter a word, no matter what they see or hear, he has Gemmata undress and pose on hands and knees, like a horse. Fondling her face, he says “This be a fine mare’s head;” then he does the same to the rest of her body parts. When he strokes her breasts, he gets an erection. He goes on to stroke her back, belly, rump, and legs. And when it’s time for the tail, he lifts his shirt, grabs his rod, and sticks it in “the place made for it,” saying “And this be a fine mare’s tail.”
With the priest in his underwear and Gemmata totally naked, the situation is getting sketchier by the minute, but Pietro and Gemmata’s investment in the magical ritual is unruffled, even as the event seems to be an excuse for the priest to fondle the woman’s naked body. In his ritual, Father Gianni does indeed seem to work a kind of magic in his ability to trade his usual sleeping companion (his horse) for the sexy Gemmata, with whom he has sex in front of her husband. In attaching the “tail,” Father Gianni places himself in the tradition of fabliaux priests who dupe gullible husbands into witnessing their own cuckolding.
Neighbor Pietro, who had been silent, exclaims that he doesn’t want the tail. Father Gianni finishes his business, then tells Pietro that this interruption ruined the magic and there’s no way to fix it. Pietro doesn’t mind, since he didn’t like the part about the tail, which the priest stuck on too low, and which he himself could have added. Father Gianni retorts that Pietro wouldn’t have known how to do it as well as he himself did. At this point, Gemmata interrupts, angry with her husband for ruining the spell and their chances of making more money. And Neighbor Pietro doesn’t ask Father Gianni for favors ever again.
While the men squabble about whose “tail” would have been more appropriate for Gemmata, she still has not understood that she has been duped. She seems more worried about the failure of the ritual than about having been raped by the priest, suggesting both an open-minded attitude towards sex (which aligns with the tales’ general disinclination to overly moralize sexual activity) but also an objectification of female sexuality, which is treated here as merely a token of exchange in payment for a magic spell.