Heliotrope

The Heliotrope is a supposedly black stone from the Mugnone whose bearer becomes invisible. Maso del Saggio presents it as a marvel, but the search it inspires exposes how readily Calandrino turns a fraudulent description into certainty. The stone’s decisive power in the episode is not magical: it gives Bruno and Buffalmacco a means to make Calandrino misread his friends’ actions, the stones striking him, and finally his wife’s ordinary recognition of him.

The Claimed Stone

Maso describes the Heliotrope as a stone of extraordinary virtue, commonly found in the Mugnone. Its size varies, he says, but its color is nearly black; anyone carrying it is supposedly unseen by other people. The particulars make the claim sound practical enough to test. Calandrino remembers the color and location, but forgets the name, treating the stone’s alleged effect as more important than what it is called.

The claim follows Maso’s other extravagant account of wonders and abundance. Calandrino has already entertained the idea of traveling to the land of Bengodi, where food supposedly falls from the sky; the Heliotrope now offers a closer marvel and a more immediate reward. Its promise is not simply invisibility but invisible access to the moneychangers’ tables, where Calandrino imagines taking as many groats and florins as he pleases. He contrasts this sudden fortune with the daily labor of plastering walls. The stone’s supposed virtue thus gives shape to a fantasy of wealth without work.

The Search Is Arranged

Rather than set out alone, Calandrino seeks Bruno and Buffalmacco, whom he especially likes, hoping that they will join the search before anyone else can get there first. He presents the discovery as a shared opportunity, but asks them to keep it secret because Maso supposedly entrusted the information to him. The secrecy, meant to protect the prize, also helps the friends control what Calandrino believes is happening.

Bruno and Buffalmacco conceal their amusement and encourage the plan. When Calandrino cannot recall the stone’s name, he argues that its appearance is enough: they should collect all the black stones they see until they find the right one. Bruno delays the search by proposing that the sun has dried the riverbed stones, making some appear white, and that passersby might guess what the three are doing. A Sunday morning, before the sun changes the stones’ appearance and when fewer people are about, would be better. The advice sounds like useful expertise, and Calandrino agrees to wait.

At daybreak on Sunday, the three leave Florence by the San Gallo Gate and descend into the bed of the Mugnone. Calandrino is the most eager and goes ahead. The arrangement has given the prank its setting and its conditions: black stones can stand in for the supposed stone, while his friends can exploit his expectation that invisibility will make their behavior seem to confirm his success.

A False Proof of Invisibility

As they proceed, Bruno and Buffalmacco speak as if Calandrino has gone home and left them to search alone. Calandrino hears them and concludes that they cannot see him because he has found the Heliotrope. Instead of calling to them or testing the stone in a way that might disprove his belief, he turns back toward home, silently delighted by what he takes to be his good fortune.

The friends continue the deception by pelting him with stones. Bruno strikes his shins; Buffalmacco hits him in the small of the back. Calandrino feels each blow, lifts his leg and puffs with exertion, but remains silent. His pain does not overturn his conclusion: because his companions behave as though they cannot see him, he interprets even their attacks as compatible with his invisibility. The stones he carries are therefore doubly misleading—ordinary flints mistaken for a wonder-working object, and weapons used to make his mistaken interpretation hurt.

At the gate, Bruno and Buffalmacco have warned the officers, who pretend not to see Calandrino as they let him pass. The staged encounter reinforces his certainty. He is carrying his collected stones, and, because it is dinner time and few people are about, nobody else accosts him on the way through the city. These circumstances help the trick hold until he reaches home near the Canto alla Macina.

The Stone Loses Its Virtue

Mistress Tessa is waiting at the stairs. Seeing her husband arrive late, she reproaches him for coming home after everyone else has dined. Her recognition punctures the illusion: Calandrino has not become invisible. But rather than accept this straightforward evidence, he blames her presence, deciding that women make things lose their virtue. He beats her in anger and threatens further violence, treating his failure to preserve the stone’s supposed power as her fault.

Bruno and Buffalmacco follow at a distance and arrive after the beating has begun. In the room, the collected stones are piled up; Mistress Tessa is bruised, disheveled, and weeping, while Calandrino sits panting and angry. He explains that he had found the stone and recounts how his companions’ words and blows seemed to prove that they could not see him. He also points to the gatekeepers’ silence and the lack of greetings from acquaintances as further evidence. The episode shows how each part of the prank has been fitted into his own account: what others stage as a joke becomes, to him, confirmation of the Heliotrope’s power.

The friends pretend to be astonished and confirm his explanation, but stop him when he rises to beat Mistress Tessa again. They argue that he alone is responsible: he should have warned her not to appear before him if women truly could destroy the stone’s virtue. Their mock reasoning exposes the fragility of the belief even as they extend the joke. The Heliotrope never receives independent confirmation as a real object with magical powers; in the evidence of the episode, its force lies in the gap between what Calandrino expects to see and what his companions arrange for him to believe. The friends eventually make peace between husband and wife, though only after the false marvel has produced a real injury.