Venomous letters: The end of Paradiso 18

Già si solea con le spade far guerra;
 ma or si fa togliendo or qui or quivi
 lo pan che 'l pïo Padre a nessun serra.

Ma tu che sol per cancellare scrivi,
 pensa che Pietro e Paulo, che moriro
 per la vigna che guasti, ancor son vivi.

Ben puoi tu dire: “I' ho fermo 'l disiro
 sì a colui che volle viver solo
 e che per salti fu tratto al martiro,
ch'io non conosco il pescator né Polo.”

Once 'twas the custom to make war with swords;
  But now 'tis made by taking here and there
  The bread the pitying Father shuts from none.

Yet thou, who writest but to cancel, think
  That Peter and that Paul, who for this vineyard
  Which thou art spoiling died, are still alive 

 Well canst thou say: "So steadfast my desire
  Is unto him who willed to live alone,
  And for a dance was led to martyrdom,
That I know not the Fisherman nor Paul (Polo)."  (18:127-136)

Paradiso 18 ends with a sting in its tail. The hesitant poet of the opening of the canto now addresses the reigning Pope, John XXII, and the attack goes deep.

This is the canto in which we along with the poet have witnessed the writing of the godhead, spelled out. Given the direct citation is the book of Wisdom, it might not be amiss to note the astrological sign for Virgo -- the goddess of wisdom, she who visited the source struck by Pegasus's hoofs:

Virgo

The "emme" the poet encounters appears overdetermined. The emphasis upon writing, upon the letter, comes to be used in the canto's conclusion with force.

Pope John XXII, the vicar of Christ on Earth, takes the pan, the sacramental body of Christ, that the Father "shuts from none," away from those he's shaking down. He does this by means of writing. In his struggle against the Fraticelli, John XXII issued the bull "Gloriosam ecclesiam" in which he excommunicated those followers of Francis who took the vow of Poverty literally.

Papal Bulls had constitutive power - they could create, or erase, the entitlement of orders, the possession and administration of property:

The majority of the "great bulls" now in existence are in the nature of confirmations of property or charters of protection accorded to monasteries and religious institutions. At an epoch when there was much fabrication of such documents, those who procured bulls from Rome wished to secure that the authenticity of their bulls should be above suspicion. A papal confirmation, under certain conditions, could be pleaded as itself constituting sufficient evidence of title in cases where the original deed had been lost or destroyed. (Papal Bull)

In a real sense, the Pope was the most powerful writer on Earth, with authority over earthly and heavenly real estate. Here in Paradiso 18 at the moment of Wisdom writing itself, the poet chooses to focus precisely upon one "who writest but to cancel." 

And Dante goes further. 

Because the Bull was so powerful an instrument, the practice of affixing to it a unique lead seal -- the bulla -- had become standard practice in the 13th century. The seal had the living pope's name on one side, and would be attached to the original document:

The most distinctive characteristic of a bull was the metal seal (bulla), which was usually made of lead, but on very solemn occasions was made of gold (as those on Byzantine imperial instruments often were: see Golden Bull). On the obverse it depicted (originally somewhat crudely) the early fathers of the Church of Rome, the apostles Peter and Paul, identified by the letters Sanctus PAulus and Sanctus PEtrus (thus, SPA •SPE or SPASPE).. . . On the reverse was the name of the issuing pope in the nominative Latin form. This disc was then attached to the document either by cords of hemp (in the case of letters of justice, and executory) or by red and yellow silk (in the case of letters of grace) that was looped through slits in the vellum of the document.

Bulla with heads of Peter and Paul

The seal authenticated the identity of the pope as author - the power of the writing, exercised through his office, was guaranteed by the bulla. For Pope John, whose existence in Avignon required a huge amount of income, the bulla was equivalent to the power to print money. With his pen, he could withhold earthly property or salvation until the desired bundle of extorted coins were delivered.

When the pope says that he's so obsessed with John the Baptist -- i.e., the inscribed head of the precursor of Christ on the florin -- that 

io non conosco il pescator né Polo 

I know not the Fisherman nor Polo, 

he meets Wisdom's definition of the fool by adoring the graven image. Boasting of not recognizing the seal of his own authority, he even fails to pronounce "Paolo" properly (flattening the dipthong as Dante may have heard Frenchmen doing). 

John is trapped in the linguistic act of abusing, confounding, and disowning the signs and meanings of his office. He has debased the very thing the poet earlier prayed the Pegasea to scrupulously respect -- the literal reality of language. 

In Avignon, John used his bastard pen to expropriate wealth and power, disowning those who professed to love Lady Poverty. Where Peter had been a fisher of men, Pope John was more a filcher, minting coinage bearing the lily of Florence and his own name on one side, the precursor of Christ on the other. The bowdlerized lily was thenceforth seamlessly linked to this pope's voice crying in the exilic desert of Avignon, prophesying salvation in gold.

Pope John XXII's Florin

Given the canto's profound concern with the duplicity of the word (verbo), it's fitting that the tail of Paradiso 18 with its venomous sting evokes yet one more "emme" with its venomous sting: the astrological symbol of Scorpio:

Scorpio