I want to contrast the Charles VI and Leber Fools in the social context of 15th-16th century Florence as revealed in novellas about madmen.
In the Charles VI Fool card, boys throw stones at the Fool, who next to them is a giant and so far does not seem to notice what the boys are doing.

It turns out that children throwing stones at Fools was a stock occurrence n Florentine novellas of the 15th and 16th centuries. A 16th century example is the story "Falananna," in Grazzini's
Le cene (which is a collection of such stories), in which a man is persuaded to pretend he is dead and so participate in his own funeral. Michel Plaisance, paraphrasing the story, notes that at one point
...people begin to think that he [Falannana] has gone mad. Children start throwing stones and clods of earth at him, showing "mad, mad" and try to catch him. Dressed in his shroud, terrified by the shouting and the stones, Falananna heads for a bridge over the Arno. To avoid a cart he climbs up onto the parapet, loses his balance, and falls into the river where he dies atrociously burnt because, to confound his misfortunes, just at that moment a "sheet of Greek fire" arrives under the bridge. Transformed into a kind of blackened stump, Falannana achieves his dehumanization to an extreme.
(This is on p. 181 of Pleasance's
Florence in the Time of the Medici. According to the author's introduction, the chapter I am citing was originally "La folie comme marquage en moyen d'exclusion dans la nouvelle florentine du XVIe siecle," in
Visages de la folie (1500-1650): domaine hispano-italien, eds. Augustin Redondo and Andre Rochon (Paris: Publications de la Sorbonne, 1981): 23-32; and then in Michel Plaisance
Antonfrancesco Grazzini dit Lasca (1505-1584). Ecrire dans le Florence des Medicis, Manziana (Rome): Vecchiarelli 2005, 123-134.)
One might wonder in the above quote if "blackened stump" was a reference to "taroccho" meaning "fool" as well as "stump," as has been discussed elsewhere in this Forum. Plaisance does not give the original Italian.
In general, the intent of the stoning was to drive the victim out of town or kill him. Of another such victim, his pursuers are
children and clerks--who, as Grazzini says, would have killed him had they caught him. (p. 184)
No penalties are mentioned for this deed. For the crowd, the victims merit this treatment not for anything they did but merely because they are mad. It appears that madmen were not welcome in Florence.
That such stonings also were part of 15th century novellas is evident in one by the artist and architect Brunelleschi (1377-1446) in which a character says
...if this were known, I would be disgraced and regarded as mad: children would purue me and I would be in great danger. Plaisnce p. 178).
And in a story by Machiavelli, a peasant offers a demon-donkey evicted from Florence "shelter in a manure heap to save him from his pursuers" (p. 176). Macchievelli portrays the peasant sympathetically throughout;, who "proves more cunning than the devil."
But Machievelli is an exception. In Florence of this time generally, the countryside was considered the place of fools and madmen. Plaisance writes
...the peasants are kept at a distance from the city by the city-dwellers who label them instance so as to justify their own actions. Boccaccio and Mateo Villani both speak of the mad peasant, the "villan matto" whose violence is a source of fear. [Footnote 3.: Boccaccio, Decameron VII, 4; Camporesi, La maschefra di Bertoldo, 33. For the differences between the words folle, passo and matto, see Croce, Le sottilissime astuzie di Bertoldo, 209.] The Florentine chronicler Paolo da Certoldo (c. 1320-post 1370) advised against confronting peasants when they formed a group: the only way to tame them, according to him, was to keep them hard at work on the land. The system of the messadria (sharecropping or metayage) made it possible to isolate peasants from one another by dispersing them int the countryside. In literature, great emphasis was placed on their ugliness and bestiality, and on their kinship with the donkey. The Sienese Gentile Sermini (active 1420s) claimed to be able to recognize peasants from their donkey's ears even when they were dressed like city dwellers. [Footnote 4. Sermini, Novelle, Story 32; see also Camporesi, La maschera di Bertoldo, 16. There is very little information available on Sermini; one of the few studies on him is Nissen, "Apostolo Zeno's Phantom Author."] ...Despite Macchiavelli's positive depiction of a peasant, Florentine culture as a whole was the culture of a city that always managed to keep its countryside well under control and was very little market by it. (p. 176).
In this demonization of the countryside, there may also be an unspoken association with the god Saturn. With his sickle, he was historically a god of agriculture, who in swallowing his children sought to prevent the next generation from suppressing his authority. As power shifts from the country to the city, he is an enemy of society. When the Charles VI Fool plays with a belt of gold medallions--rather like the gold chains worn as a necklace by the privileged, as in a Titian portrait at
http://www.artsunlight.com/artist-NT/N- ... html--that perhaps is taken as an illegitimate and threatening aspiration. (For more on the Fool as Saturn, see the "Fool" thread in Bianca's Garden here.)
But the stories of the 15th and 16th centuries take a different twist, subversive of the city's power. The protagonists, usually lower-class city-dwellers or country people in the city, are are made to appear mad by a coordinated conspiracy of upper-class practical jokers called
beffatori (from
beffa, practical joke). For one reason or another, usually self-serving, one of their group wants to remove the object of their jokes from the city. In this respect, they are like the insects buzzing around the Fool's head. Their practical jokes infuriate the object of their prank, thus serving to confirm their labeling of him as mad. As a mad person, he is not subject to the law. But apparently he is not protected by the law either, for then the children can be unleashed on him with impunity. (Like the card, he is not even the lowest member of society; he is outside the social structure altogether.) In the context of the increasingly authoritarian regimes of the later Medici, the reader's sympathy is with the so-called "fool" who is powerless against the illusionists.
In the changing context, the message of the Fool card perhaps also changes. Whereas in the Charles VI, our sympathy is with the Fool because his genial nature (like that of the peasant) does not justify the attacks on him by the boys, in the Leber, the Fool, i.e. peasant or worker (or nonconforming humanist) is right to defend himself against his tormentors; however his weapons are inadequate for the job, and so appears as a fool if he rebels.