Ambrogiuolo’s fabricated proof of Ginevra’s adultery transforms a merchants’ argument into a wager whose false evidence puts an innocent woman’s life at risk. By secretly entering her bedroom, stealing her belongings, and learning a private bodily mark, Ambrogiuolo manufactures the appearance of sexual access without ever seducing Ginevra. His staged proof persuades Bernabo Lomellini that his wife has been unfaithful, demonstrating how easily intimate knowledge and material traces can be made to serve a lie.

The Argument Becomes a Wager

The deception begins in Paris as a dispute between merchants about whether women can be trusted to remain chaste. Ambrogiuolo argues that women may yield to desire if they can do so secretly and without damage to their reputations. He claims to have tested this belief with many women and boasts that he could quickly seduce Bernabo’s wife, whom Bernabo regards as exceptionally discreet and careful of her honor. Bernabo counters that a woman who values her reputation can be stronger than a man who does not, and insists that his wife belongs to this faithful kind.

Rather than let the argument continue as a contest of assertions, Bernabo proposes a wager. He stakes his head against Ambrogiuolo’s thousand gold florins, but Ambrogiuolo refuses to accept the danger of killing Bernabo if he wins. He raises the stakes: Bernabo must put up five thousand gold florins against Ambrogiuolo’s thousand. Ambrogiuolo also sets a three-month limit and promises to return with Ginevra’s precious possessions and enough tokens to make Bernabo acknowledge his victory. The merchants present try to prevent the wager, foreseeing that it may lead to grave harm, but the two men formalize their agreement in writing. Bernabo agrees not to go to Genoa or write to his wife during the term, removing the possibility that he might warn her or interfere with Ambrogiuolo’s scheme.

A Bedroom Entered by Deception

Ambrogiuolo goes to Genoa and cautiously learns where Ginevra lives and how she conducts herself. What he discovers confirms, rather than weakens, her reputation for restraint. Unable to approach her directly, he pays a poor woman who moves in and out of the household and is Ginevra’s well-wisher. Ambrogiuolo persuades her to carry him into the house inside a specially made chest. The woman leaves the chest in Ginevra’s bedroom, ostensibly while she is away, and Ambrogiuolo waits until night to emerge.

A lamp is burning in the room. Ambrogiuolo uses its light to memorize the arrangement, the paintings, and other distinctive details, making the room itself part of his future performance. Ginevra is asleep with a little girl beside her. He uncovers Ginevra and observes her, but finds no visible trace to take away except a mole beneath her left breast, surrounded by several small hairs as red as gold. Though he is tempted to risk lying beside her, he does not do so; he knows her reputation for refusing sexual advances and chooses not to gamble on an actual attempt. The distinction is decisive: his claim will depend not on an affair, but on details gathered through covert observation.

For two nights he repeats the intrusion without Ginevra’s knowledge. He takes a purse, a night-rail, rings, and girdles from one of her coffers, then returns to the chest and conceals himself inside it. On the third day, the woman retrieves the chest and carries it away. Ambrogiuolo rewards her as promised and hastens back to Paris, arriving before the wager’s deadline. His access to the bedroom has yielded both portable objects and private knowledge, which he can now present as the residue of intimacy.

The False Proof and Bernabo’s Response

Ambrogiuolo summons the merchants who witnessed the wager and makes his claim in Bernabo’s presence. First, he describes the bedroom’s arrangement and paintings. Then he produces the belongings taken from Ginevra’s room, falsely asserting that she gave them to him. Bernabo recognizes the room and confirms that the objects are his wife’s, but initially points out that Ambrogiuolo might have learned the room’s appearance from a servant and acquired the goods by other means. The stolen possessions and accurate description create suspicion, but Bernabo does not yet accept them as conclusive proof of adultery.

Ambrogiuolo supplies the detail he has reserved: the mole beneath Ginevra’s left breast and the red hairs around it. Bernabo’s anguish shows that this knowledge overwhelms his remaining doubt. His changed expression gives the assembled merchants visible confirmation that the detail is true; he concedes the wager and pays Ambrogiuolo in full the next day. Yet the mark establishes only that Ambrogiuolo saw Ginevra while she slept. The narrative has shown how he entered her room, watched her, and refrained from approaching her. The apparent proof of sexual access is therefore knowledge obtained through intrusion, not evidence of consent or an affair.

Consequences and Narrative Significance

After collecting the five thousand gold florins, Ambrogiuolo has won the public dispute by presenting an interpretation of his evidence that Bernabo accepts. Bernabo leaves Paris and travels toward Genoa with murderous intent. Rather than enter the city himself, he stops at a country house about twenty miles away and sends a trusted servant to summon Ginevra, while privately ordering the servant to kill her on the journey. The fraud thus moves beyond damaged trust or financial loss: a stolen garment, several ornaments, a bedroom description, and one bodily detail become the grounds for an attempt on Ginevra’s life.

The episode turns on the gap between what Ambrogiuolo knows and what he claims that knowledge proves. His details are accurate, but their accuracy conceals the means by which he obtained them. The chest makes the deception possible; the objects give it material weight; the mark makes Bernabo’s doubt collapse. Against Ginevra’s actual fidelity, Ambrogiuolo’s performance exposes how a reputation for chastity can be attacked through evidence that appears intimate while masking coercive observation and theft. The wager’s consequence is not a verdict reached through investigation, but a husband’s conviction—and the danger that follows from treating possession of private knowledge as proof of a wife’s betrayal.