Calandrino, a Florentine painter, is a popular character in several stories of the eighth and ninth days. Based on a real painter, Nozzo di Perino, his simplemindedness, quaint ways, and strong affinity for all types of folk magic makes him the target of Bruno and Buffalmacco's jokes. Their magic, which Calandrino believes exerts strong influences on him, is merely a sham. Calandrino thinks the heliotrope he collects along the banks of the Mugnone renders him invisible, but really all he gets is a stoning by his friends on the way home. Maso del Saggio tells him, 'There are two kinds of stones that are very magical indeed. First of all we have the sandstones of Settignano and Montici, from which, when they are turned into millstones, we get all our flour; Now, the second...has the miraculous power of making people invisible when they are out of site, provided they are carrying it on their person."
"Amazing!" said Calandrino.
In VIII.6 Calandrino hopes to regain his pig through the "bread and cheese test." "Tonight," Bruno says, "I shall cast a spell on the sweets, and bring them round to your house first thing tomorrow morning." He ensures the spell's efficacy by adding he will "pronounce all the right words and do all the right things." But Calandrino, thoroughly taken in, indicts himself in front of his neighbors. He fails the test, and loses his pig, money, and capons as well.
In IX.3 Calandrino is tricked into thinking that he is pregnant and, after taking a potion, believes it to have been effective: "He bestowed high praise on Master Simone for his miraculous cure, which in only three days had effected a painless miscarriage."
Novella IX.5 centers around his belief that an enchanted scroll can win Niccolosa's affections. The ingredients needed for the preparation of the scroll are those which could be in any spell-like recipe, including, "a small piece of parchment from a stillborn lamb, a live bat, three grains of incense, and a candle that has been blessed." The "meaningless hieroglyphics" with which Bruno fills the parchment become an indication of Boccaccio's attitude toward this type of magic.