Roasted Saint
When the time comes for Fra Cipolla to preach his sermon, he opens the box and notices that it is full of coals. To save himself from an embarrassing situation, he thinks fast and comes up with a story. He tells the congregants that he has confused the box containing the feather with another identical box, which contains coals. He then claims that the coals were used when Saint Lorenzo was roasted. And since the feast of Saint Lorenzo is coming up soon, the friar declares that it is a sign from God. Everyone believes him, and Giovanni and Biagio return the feather after the sermon.
Before moving on to the role of the coals and the feathers, you might be interested in a comparison with The Pardoner’s Tale from The Canterbury Tales written by Geoffrey Chaucer who took inspiration from the novella about Fra Cipolla. And there is more. If you want to dive into the coals and feather, then go to the next step.