- a classical/contemporary couple: Ulysses and Guido da Montefeltro
- Ulysses recounts a failed quest, Guido recounts a failed conversion; both stories are structurally central to the plot of the Commedia
- what language does Virgilio speak?
- historical torture versus metaphoric torture
- tirannia reprised (see Introduction to Inferno 12)
- Guido’s story involves a second actor, Boniface VIII (for Boniface, see Introduction to Inferno 19)
- Christian doctrine on repentance wedded to Aristotelian logic: the law of non-contradiction (A ≠ not A)
- disconversion as a means for meditating on the laws that govern conversion
- the little temporal adverbs that are the linguistic correlatives of conversion, as in Augustine’s Confessions: conversion follows the arrow of time
- both Petrarch and Boccaccio understand Inferno 27 as a meditation on conversion and disconversion: the connections of Guido da Montefeltro’s story to Petrarch’s Rerum vulgarium fragmenta and to Boccaccio’s Decameron
 Inferno 27 is the second of two canti devoted to the sin of fraudulent counsel. In this bolgia, as elsewhere in Malebolge, we see a classical figure (Ulysses in Inferno 26) paired with a contemporary figure (Guido da Montefeltro in Inferno 27). Atypically, however, and creating a different narrative dynamic, both Ulysses and Guido are great characters: each dominates an entire canto, and each tells a story that is structurally central to the plot of the Commedia. Ulysses recounts a failed quest, while Guido recounts a failed conversion.
 In Inferno 27 we have the opportunity to observe how Dante goes about transposing fraudulent counsel from the heroic/epic/classical key of Ulysses to the vernacular/ contemporary/quotidian key of Guido da Montefeltro. As we shall see, Dante will “transpose” the key of this canto by literally transposing the language that Virgilio speaks.
 The canto of Guido da Montefeltro functions in many ways as an unmasking of the canto of Ulysses. As Inferno 16 serves to demythologize Inferno 15, focusing on the physical degradation of the three noble Florentines in a way that does not occur vis-à-vis Brunetto Latini, so Inferno 27 demythologizes Inferno 26. The difference between Dante’s treatment of Ulysses and his treatment of Guido is immediately apparent.
 The travelers are beginning to move off after Ulysses has finished speaking, when another flame comes after them, emitting a “confuso suon” (perplexing sound [Inf. 27.6]): instead of Virgilio’s lengthy and beautiful captatio benevolentiae, here it is the sinner who begs the travelers to remain, and instead of Ulysses’ sonorous exordium, here there is only a confused racket. Dante now elaborates on the modus operandi of this speaking flame, something he chose not to do in Inferno 26, and there follows the graphic horror of the simile of the Sicilian bull.
 This is the bronze bull in which the tyrant Phalaris of Sicily roasted his victims, whose shrieks were transformed by the machine into the bellowing of a bull. As the tortured victims in the bull attempt to wail, but have their human cries transformed into a bull’s bellowing (a further degradation to amuse the tyrant), so the soul within the flame attempts to speak, but can find no outlet for his voice (Inf. 27.7-15). An artistic emphasis symptomatic of Malebolge is built into the simile, by way of the reference to the bull’s inventor, Perillos of Athens, and his just punishment (verses 8-9).
 The simile of the Sicilian bull functions as a transforming medium. The simile is stationed at the outset of Inferno 27 in order to transform the discourse: to accomplish the transition from high to low, from epic to quotidian, from human to bull. The issue at stake here is transformation; it is conversion, as the verb convertire in verse 15 indicates.
 This transformation is articulated at the level of language, as is appropriate in an infernal pit inhabited by tongues of fire. The simile articulates the transition from speech, the “high” epic speech of Virgilio and Ulysses in Inferno 26, to the “low” sound of a bull’s bellows. The simile’s second term describes the “conversion” of Guido’s words into “the language of the fire”: “in suo linguaggio / si convertian le parole grame” (the miserable words were converted into the flame’s language [Inf. 27.14-15]). Dante uses the transformation of human speech into a bull’s bellows as a means of engaging the canto’s theme: conversion.
 Only now do we understand that Ulysses’ voice, like Guido’s, must have been physically degraded by the effort of speaking as a flame. Only now do we understand the physical effort that is implied by “gittò voce di fuori” (he threw forth his voice [Inf. 26.90]). Only now do we realize that Ulysses’ eloquence, like that of Pier della Vigna, who emitted “parole e sangue” as he spoke, was accompanied by great pain.
 This passage is followed by another tercet describing the mechanics of Guido’s speech, and then, finally, by his first words: a subversive apostrophe addressed to Virgilio, referring to the maestro’s recent dismissal of Ulysses. This dismissal was already mentioned in verse 3, where Ulysses’ flame departs “con la licenza del dolce poeta” (with the permission of the gentle poet [Inf. 27.3]). We have noted Dante’s love of the telling periphrasis, and Guido now uses a linguistic periphrasis to address Virgilio: Virgilio is the one “who was just now speaking Lombard“ (“che parlavi mo lombardo” [Inf. 27.20]) and who was saying “‘Istra ten va, più non t’adizzo” (Go away now, I urge you no more [Inf. 27.21]). If it is surprising to learn that Virgilio, who had addressed Ulysses with such manifest respect in Inferno 26, should dismiss him with the words “Go away now”, it is even more surprising to find these words recorded in a coarse Lombard dialect:
udimmo dire: “O tu a cu’ io drizzo la voce e che parlavi mo lombardo, dicendo ‘Istra ten va, più non t’adizzo’” (Inf. 27.19-21)
We heard: “O you to whom I turn my voice, who only now were talking Lombard, saying, Go away now, I urge you no more’”
 As I wrote in Dante’s Poets, “We now see what transformation the Sicilian bull has prepared us to accept: Vergil’s ‘S’io meritai di voi’ has become ‘Istra ten va’; the high style has been converted to the low style” (p. 231). Indeed, Virgilio’s high, sonorous, Latinate “S’io meritai di voi” of Inferno 26 has become low, clipped, coarse Lombard dialect — “Istra ten va” — in Inferno 27.
 On the subject of Virgilio speaking Lombard, we recall that he is a Lombard native, as stipulated in “li parenti miei furon lombardi” (my parents were from Lombardy [Inf. 1.68]). Consequently, we must also wonder: did Ciampolo offer to call “Toschi e Lombardi” (Tuscans and Lombards [Inf. 22.99]) out of the grafters’ pitch because he heard Virgilio speaking Lombard? And, if so, what form of Lombard did Ciampolo hear?
 Although linguistic diversity is a fictional premise of Dante’s afterlife, inhabited by people who speak “Diverse lingue, orribili favelle” (“Different languages, horrible tongues” [Inf. 3.25]), it is not a narrative premise, in that almost everyone speaks in the language in which the poem is written. Dante frequently approximates the speech of his characters in his Italian (a gallicism for Hugh Capet, regional dialectisms where appropriate), and occasionally employs other languages (Provençal for Arnaut Daniel, Latin for Cacciaguida), but, as Antonino Pagliaro points out: “si tratta di caratterizzazione di ordine, non linguistico, ma stilistico” (this form of characterization is not linguistic, but stylistic; see “Dialetti e lingue nell’oltretomba,” cited in Coordinated Reading).
 What language did Dante imagine the historical Vergil spoke? Ettore Paratore convincingly demonstrates that Dante recognized a Latin vernacular as the root of the Romance vernaculars. Dante would further have believed, according to the thesis he lays out in his linguistic treatise De vulgari eloquentia, that the literary Latin of the classical poets was abstracted from spoken Latin, in the same way that literary Italian was abstracted from spoken Italian (see Paratore, “Il latino di Dante,” cited in Coordinated Reading). According to Paratore, Dante imagined that Vergil spoke a vernacular form of the gramatica in which he wrote (see De vulgari eloquentia 1.3 for gramatica), i.e. a vernacular form of Latin. I therefore suggest that Virgilio’s “Lombard” is a reference to the vernacular Latin that Dante believed the Roman poet spoke while alive, a “Lombard Latin” as it were. For more bibliography on the linguistic issues at stake in this passage, see the long note in Dante’s Poets, p. 232.
 Linguistic issues are inevitably represented by stylistic shifts in Inferno 26 and 27, for Dante does not have the means to represent real linguistic change. In other words, although we do not know in what language Virgilio originally spoke to Ulysses (i.e. whether Guido’s reference to Virgilio’s “Lombard” applies only to his last dismissal, or to his previous address as well), we do know that he originally spoke in a high style, and is now represented as speaking in a low one.
 Dante necessarily works within the constraints of his medium, which is the Italian vernacular. In Inferno 26 he ennobles the style and diction of spoken Italian, as used by both Virgilio and Ulysses. When, instead, Guido da Montefeltro says that he heard Virgilio say “Istra ten va, più non t’adizzo” (Go away now, I urge you no more [Inf. 27.21]), it is as though Dante has literally “translated” the style and register of vernacular Italian from the mode of tragedìa (Inferno 26) to the mode of comedìa (Inferno 27).
* * *
 The Sicilian bull is a likely historical instrument of torture recorded by classical authors as devised for Phalaris, the real tyrant of Agrigento, in Sicily. Phalaris ruled circa 570 to 554 BCE and was known to Aristotle, who notes his depravity and cites him as an example of bestiality in Nicomachean Ethics 7.5.
 Along with the Sicilian bull, there are other real tortures cited in Inferno. In Inferno 19 Dante stands over Nicholas III stuck head-first in the floor of Hell and compares himself to a friar who confesses an assassin (Inf. 19.49-51). Dante is referring here to the capital punishment meted upon paid assassins, called propagginazione, which consists of burying the criminal head-first in a hole, filling the hole with dirt, and creating death by suffocation. In Inferno 23.66 Dante compares the leaden capes worn by the hypocrites to the lead mantle supposedly devised as an instrument of torture by Frederick II (there is no documentary confirmation of this torture, whose alleged connection to Frederick is repeated by all the ancient commentators). In Inferno 28.80, Dante refers to a form of torturous murder committed on board ships: called mazzerare, this torture consists of putting a living man in a sack with a heavy rock, tying the sack, and throwing it overboard. In Inferno 30.75, Maestro Adamo reports having been burned alive on the stake: “per ch’io il corpo sù arso lasciai” (for this I left my body, burned, above [Inf. 30.75]).
 Dante-narrator will suggest in Purgatorio 27 that he had witnessed both propagginazione and burning at the stake. He references the pallor of one who is condemned to being buried alive: “colui che ne la fossa è messo” (one who is placed in the ditch [Purg. 27.15]). Shortly thereafter he mentions having seen human bodies set alight: “umani corpi già veduti accesi” (the human bodies I’d once seen burning [Purg. 27.18]). Interspersed with the literalized metaphors that Dante devises as contrapassi, representations that have always captured the attention of his readers, there are thus historical forms of torture that Dante knew about and even witnessed.
 In the context of Inferno 27, the Sicilian bull and the tyrant who deployed it anticipate the first part of the pilgrim’s dialogue with Guido da Montefeltro, which will treat the spread of tirannia as a form of governance throughout the cities of Romagna. On tirannia, see the Introduction to Inferno 12.
 Realizing that Dante is Italian, Guido da Montefeltro asks whether his native Romagna experiences peace or war. Going city by city through the region, Dante explains that, although there is no outright war at present, Romagna is never free of war “in the hearts of its tyrants”: “Romagna tua non è, e non fu mai, / sanza guerra ne’ cuor de’ suoi tiranni” (Your Romagna is not now and never was / quite free of war inside its tyrants’ hearts [Inf. 27.37-38]).
 This meditation on the birth of tyrannical rule in Italy features a list of Romagnol dynasties that includes both Francesca da Rimini’s birth family, the Polentani, and the family into which she married, the Malatesta (Inf. 27.41 and 46 respectively). In verses 46-48, Dante pungently describes the cruelty of the founder of the Malatesta dynasty, Malatesta da Verucchio, and his son, Malatestino, who became lord of Rimini after his father’s death. In the next canto, Dante adds to the indictment of this dynasty, calling Malatestino a “tiranno fello” (foul tyrant [Inf. 28.81]) for his ghastly murder of the two best citizens of Fano.
 Guido da Montefeltro himself was a great warlord and political strategist who founded the ruling dynasty of Urbino, and whose role in shaping the destiny of the Romagna region has been insufficiently considered in discussions of Inferno 27. In The Malatesta of Rimini and the Papal State, historian P. J. Jones notes that the ‘‘transformation of local into regional signoria was mainly the work of one man”: this man was Guido da Montefeltro. In my essay “Only Historicize” I cite Jones and consider how such an understanding can transform our reading of Inferno 27:
Reading historians of Romagna allowed me to glimpse the remarkable and unexploited historical density of Dante’s poetry in Inferno 27: the drama of Guido da Montefeltro’s false conversion in the canto’s latter half is ripe for a reexamination that reads his story against the canto’s earlier probing of Romagnol history. In The Malatesta of Rimini and the Papal State, the historian P. J. Jones writes of Guido’s impact on Romagna that the ‘‘transformation of local into regional signoria was mainly the work of one man’’.
Even the imagery of Inferno 27 can be contextualized with respect to contemporary politics: for instance, Jones mentions a Ghibelline poem that ‘‘sets out to contrast the two captains, Guido ‘leone’ and Malatesta da Verucchio ‘veltro’ ’’ (34), while in Inferno 27 Malatesta is a mastiff rather than a veltro, and Guido famously says that his deeds ‘‘non furon leonine, ma di volpe’’ (Inf. 27.75). When the pilgrim, speaking to Guido da Montefeltro in Inferno 27, refers to the ‘‘lunga prova’’ endured by Forlì before it reduced the French to a ‘‘sanguinoso mucchio,’’ he is referring to events in which historians assign that same Guido da Montefeltro the central role. And yet there has not been a reading of Dante’s Guido da Montefeltro that takes into account his crucial role in a historical process — the formation of tirannia — that Dante deplored. (“Only Historicize,” pp. 48-49)
* * *
 Dante praises Guido da Montefeltro in Convivio 4.28.8 for having renounced worldly ambitions in old age to become a Franciscan friar. In Inferno 27, Dante uses the same template — renunciation of worldly ambition and embrace of a friar’s life — but dramatically refashions it. The result of Dante’s refashioning is that Guido’s story holds up a mirror to the Commedia’s central theme: conversion.
 Disconversion is a necessary predicate to a meditation on conversion, and in the Commedia Guido da Montefeltro tells a devastating story of failed conversion.
 Both Petrarch and Boccaccio understand Inferno 27 as a meditation on conversion and disconversion, as I discuss at the end of this Introduction. Their responses signal that the importance of Inferno 27 for Dante’s contemporaries is philosophical and not keyed to what Dante did or did not learn from chroniclers with respect to Guido’s life.
 Guido prefaces his story with lines made famous by the poet T. S. Eliot, who uses Inferno 27.61-66 as the epigraph to “The Love Song of J. Alfred Prufrock”, thus offering me and many others our first encounter with Dante’s poetry. Eliot does not identify the author or provenance of the verses he cites. I still remember my youthful encounter with language that I found even more hauntingly beautiful than Eliot’s and my father’s explanation that this was Dante.
 Guido begins his address to Dante with a conditional contrary to fact (verses 61-63), followed by a mistaken deduction from a false premise (verses 64-66). If he thought that he were speaking to someone able to go back to earth, says Guido to Dante, then he would be silent; but, since he has heard that no one exits from this pit, he will speak without fear of infamy:
S’i’ credesse che mia risposta fosse a persona che mai tornasse al mondo, questa fiamma staria sanza più scosse; ma però che già mai di questo fondo non tornò vivo alcun, s’i’ odo il vero, sanza tema d’infamia ti rispondo. (Inf. 27.61-66)
If I thought my reply were meant for one< who ever could return into the world, this flame would stir no more. And yet, since none, if what I hear is true, ever returned alive from this abyss, then without fear of facing infamy, I answer you.
 Guido’s over-confident susceptibility to false premises — the very susceptibility that will be exploited by Boniface VIII — is already visible in this opening passage, where the false premise of his argument is that no one ever exits Hell. Guido weighs whether to tell his story to Dante and carefully calculates that, based on the false premise he has accepted as true, he is safe and may therefore speak. Guido errs in his prudential calculation, of course, since Dante is the one traveler who does leave this pit.
 Guido’s miscalculation vis-à-vis the pilgrim is a mise-en-abyme of the erring prudential calculation that delivered him to Hell in the first place. His error is revealed in his syntax, in the conditional contrary to fact and the causal conjunctions plus temporal adverbs of verse 64: the words “ma però che già mai” — “given that never before” — give the impression of ironclad reasoning, but in truth the reasoning is faulty.
 Similarly, Guido’s plan to guarantee salvation by becoming a Franciscan was, he thought, ironclad. It would have succeeded but for, in his telling, the “High Priest” who lured him back into sin:
Io fui uom d’arme, e poi fui cordigliero, credendomi, sì cinto, fare ammenda; e certo il creder mio venìa intero, se non fosse il gran prete, a cui mal prenda! che mi rimise ne le prime colpe. (Inf. 27.67-71)
I was a man of arms, then wore the cord, believing that, so girt, I made amends; and surely what I thought would have been true were it not for the High Priest—may he be damned— who made me fall back into my former sins.
 The “gran prete” whom Guido da Montefeltro damns in verse 70 will indeed be damned, according to Dante, for Guido is referring to Boniface VIII, the very pope whom Dante condemns for simony in Inferno 19. However, Guido here is damning himself: for he is revealing that his conversion was not real, but prudential. Boniface could not have compelled him to return to his “prime colpe” (former sins [Inf. 27.71]) had he truly converted and left those sins behind.
 The verb mettere in the past absolute is used by both Ulysses and by Guido in key verses that are emblematic: of Ulysses’ failed adventurism on the one hand and of Guido’s failed conversion on the other. Ulysses speaks of himself as in control, the agent of his destiny who sets out boldly onto the open sea: “ma misi me per l’alto mare aperto” (I set out on the open sea [Inf. 26.100]). Guido instead speaks of Boniface VIII as agent, the one who turned him back to his old bad ways: “mi rimise ne le prime colpe” (he made me fall back into my former sins [Inf. 27.71]).
 In this respect, Ulysses is unusual in Inferno while Guido da Montefeltro is typical: it is typical of Dante’s sinners, beginning with Francesca, to shift the blame for damnation from oneself.
* * *
 While Ulysses‘ journey to death and damnation is one of isolated grandeur in both decision-making and execution (the crew are but his pawns, in his telling), Guido da Montefeltro’s story involves a second actor. The story Guido tells is therefore in some ways more layered and complex, involving a double set of motivations.
 According to Guido, Boniface sought counsel from the old warrior on how to conquer Palestrina, the stronghold of his Colonna enemies. The Colonna cardinals had refused to accept the legitimacy of the abdication, in 1294, of Boniface VIII’s predecessor, the holy Benedictine hermit, Celestine V. Consequently, they did not accept the legitimacy of Boniface VIII’s reign, and the result was the brutal papal seige of the Colonna stronghold at Palestrina. Boniface VIII is thus another tiranno to add to the list of tyrants offered earlier in this canto.
 When Boniface sees that Guido hesitates to give him the counsel he requires, the pope reassures the retired condottiere that he need not fear for his soul. At this point Boniface gives false counsel, for he lies, telling Guido da Montefeltro that as pope he has the power to absolve and — here is the lie — that he will absolve Guido of his future sin immediately, from this very moment:
E’ poi ridisse: “Tuo cuor non sospetti; finor t’assolvo, e tu m’insegna fare sì come Penestrino in terra getti. (Inf. 27.100-02)
And then he said: “Your heart must not mistrust: I now absolve you in advance —— teach me to batter Penestrino to the ground.
 In a most remarkable instance of layering, Dante provides us with a troping of fraudulent counsel in this episode, for the fraudulent counselor Guido da Montefeltro relates that he was fraudulently counseled by Boniface VIII. Boniface gave Guido fraudulent advice when he tells him not to worry about sinning, promising that he will absolve him in advance, before he sins: “finor t’assolvo” (I now absolve you in advance [Inf. 27.101]). Boniface offers apparently prudential logic based on a false premise, for not even a pope can absolve for a sin that has not yet been committed.
 Boniface of course knows that one cannot be absolved of a sin before committing it. (However, theology runs afoul of history: for a historical example of papal absolution offered in advance, see Appendix 1 below.) The logic here is simple: commission of a sin requires the soul to will to carry out the sin, and it is not possible to will an act and repent of that act simultaneously. It is this simultaneous repenting and willing that is challenged by the devil who arrives to take Guido’s soul to Hell, snatching him from St. Francis in the final episode of his story that Guido relates at the canto’s end.
 The devil unites in his analysis both elementary Christian doctrine — absolution requires repentance — and elementary Aristotelian logic: we cannot simultaneously want to commit an action and want not to commit it.
 As the devil points out, this argument presents a logical fallacy, based on the law of non-contradiction. The law of non-contradiction — which Dante states explicitly in Paradiso 6, verse 21, also in the context of conversion (see Appendix 2 below) — holds that a true statement and its opposite cannot both be true at the same time in the same sense. This principle is stated in logic as A ≠ not A:
ch’assolver non si può chi non si pente, né pentere e volere insieme puossi per la contradizion che nol consente (Inf. 27.118-120)
one can’t absolve a man who's not repented, and no one can repent and will at once; the law of contradiction won't allow it.
 A final thought on Boniface VIII. As discussed in the Introduction to Inferno 19, Boniface did not die until 1303, and Dante therefore has to go to great lengths to insert him into a Hell that the pilgrim visited in April of 1300. In doing so, he denies Boniface the possibility of repentance in extremis (the very possibility that he grants to Guido da Montefeltro’s son, Bonconte, in Purgatorio 5) and flirts dangerously with determinism. The pope promises absolution for a sin not yet committed, and Dante in turn has promised him damnation for a life not yet fulfilled.
 Nonetheless, Boniface’s sins are not the point here. They are invoked by Guido to exculpate himself but they should not distract us, as they do not distract the devil who arrives for Guido’s soul in the scene described at the canto’s end. In giving Boniface the evil advice he seeks, Guido shows that he has not really converted, that he has not really changed his essence.
 In Dante’s account, Guido had abandoned his life as a warrior and politician, and yet his sinful inclinations were so strong that he was susceptible to the temptation posed by Boniface VIII. His conversion did not “take”: he was tempted and he fell. In Hell he is furious at the man who outwitted him and regretful that his brilliant plans to achieve salvation were thwarted. But the issue is not truly Boniface; the issue is what Boniface revealed about Guido.
 Guido da Montefeltro put great effort into taking the steps that he thought would guarantee his salvation, renouncing his worldly life to become a Franciscan. Yet he fails, because his heart did not change. His son Bonconte, whose story Dante recounts as a counterpoint to the father in Purgatorio 5, remained a warrior until his end, dying on the battlefield. And yet, by uttering a genuine prayer of repentance with his last breath, Bonconte achieves salvation.
* * *
 Inferno 27 is a touchstone for Petrarch, whose depiction of his own struggle to achieve conversion is influenced by the episode of Guido da Montefeltro. As shown by Augustine in the Confessions and by Dante in Inferno 27, the logic of conversion follows the arrow of time. While Dante goes to great lengths in Inferno 27 to embed conversion and its causality in a temporal process that follows the arrow of time, Petrarch deliberately subverts time and forward motion in his Rerum vulgarium fragmenta, the lyric sequence that recounts his own failure to achieve conversion.
 When Guido blames Boniface for reconsigning him to his “prime colpe” (my former sins [Inf. 27.71]), for sending him back to the state he was in before he became a Franciscan, he effectively acknowledges that he did not truly convert. Had he truly converted, had he truly changed his essence, he could not have gone backwards; he could not have returned to his previous self.
 Petrarch, who writes of his “primo giovenile errore” (first youthful error) in the first poem of the Rerum vulgarium fragmenta and tells us repeatedly in poem after poem that he is never truly able to leave the “primo alloro” (first laurel [Rvf 23.167]), adapts the deep logic of Guido’s story to himself. Petrarch dramatizes himself as the protagonist of a failed conversion, based on his inability to move forward, from primo to something that comes later. His first sonnet, Voi ch’ascoltate, features repentance via the same unusual form of the verb (pentére) used by Guido da Montefeltro. In a replication of Guido’s failed logic, Petrarch places a poem of “repentance” before a lyric sequence that subsequently and repeatedly celebrates the very act for which he has “already”, in sonnet 1, declared his repentance. As I note in “The Self in the Labyrinth of Time”, Petrarch is replicating Guido’s time-line, “repenting” before sinning:
A recantation — “’l pentérsi,” repentance (1.13) — at the outset makes no more sense than a sinner’s attempt to repent before sinning, a logical contradiction treated by Dante in the Guido da Montefeltro episode of the Inferno (via the same unusual form of the verb, pentere, used in Voi ch’ascoltate by Petrarch): “ch’assolver non si può chi non si pente, / né pentere e volere insieme puossi / per la contradizion che nol consente” (For he who does not repent cannot be absolved, nor can one both repent and will at once, because of the contradiction which does not allow it [Inf. 27.118–20]). “Forse / tu non pensavi ch’io loïco fossi” (Perhaps you did not think I was a logician! [Inf. 27.122–23]), says the devil to Guido as he drags him off to hell. As shown by Augustine in the Confessions and by Dante in the Commedia, and as Petrarch well knows, the logic of conversion follows the arrow of time: it is not logical to renounce the “breve sogno” before engaging in it, before succumbing to it, before representing it. (“The Self in the Labyrinth of Time: Rerum vulgarium fragmenta,” p. 42)
* * *
 At the heart of Guido’s story are Augustinian temporal adverbs that he weds with causal conjunctions. Boniface says “finor t’assolvo” — “from now I absolve you” — and Guido echoes in response, making his fatal error when he links the causal conjunction “da che” (since) with the temporal adverb “mo” (now): “Padre, da che tu mi lavi / di quel peccato ov’ io mo cader deggio” (Father, since you cleanse me of the sin / that I must now fall into [Inf. 27.108-109]). The tiny particle “mo” is the crux of matter: it signals that Guido accepts the idea that he can receive prior absolution for the sin that he will only “now” — “mo” — commit.
 But, as the devil reminds us, absolution requires repentance, and it is not possible to repent for an act that one has not yet committed: the logic of sin and repentance, and therefore of conversion, is temporal.
 Guido uses the lexicon of repentance and conversion, but he scrambles the order — fatally. If we were to take the lexicon of repentance and conversion of Inferno 27 and unscramble it, we could achieve what Guido did not achieve, the following proper temporal alignment:
1) volere (verse 119: desire, in this case the desire to sin) → 2) the commission of sin (described in verses 110-11) → 3a) pentére (verse 119: repentance for the sinful act committed) → 3b) confession following repentance (as in verse 83: “pentuto e confesso mi rendei”) → absolution (as in Boniface’s “finor t’assolvo” of verse 101, but without the incriminating temporal adverb “finor”)
 In the above logically sequential order, the words are not mere shells, like poker chips in a game. They are related to authentic feelings and they therefore unfold in time, in the only possible order: 1) first comes the will to sin (volere); 2) then comes the commission of the sin; 3) then comes repentance (pentére) with its partner confession; 4) finally one is absolved. In a sequence in which words are connected to authentic feelings, we can see the absurdity of Boniface’s “finor t’assolvo” (101).
 In Boniface’s impossible sequence, which Guido accepts only because he has not lost the desire to sin, the words are robbed of meaning and have become formal shells, to be manipulated at will. Indeed, Boniface takes pride in his manipulation of people, announcing “Lo ciel poss’io serrare e diserrare”: “Heaven can I lock and unlock” (Inf. 27.103). When the words have meaning, when they correspond to genuine sentiment, then they can proceed only in one direction, because of the nature of desire and its unfolding in time.
 The theatricality of the scene in which St. Francis arrives for the soul of one of his Franciscans, only to be dismissed by the logic-wielding devil, is reminiscent of mystery plays and popular medieval drama. The logic of conversion is so unassailable that not even St. Francis can prevail. The theatricality also reminds us that conversion is precisely not a performance art: conversion happens not outside, as performed by Guido da Montefeltro in Inferno 27, but inside, and we cannot read what is happening inside the soul. Not even a church dignitary can do so: hence the archbishop of Cosenza, delegate of Pope Clement IV, mistakenly condemned the saved Manfredi, as Dante carefully points out in Purgatorio 3.
 Repentance, conversion, and salvation remain opaque, hidden in the human heart, mysterious and known only to God, as Boccaccio brilliantly reminds us in the first novella of the Decameron (a novella that also owes much to Inferno 27):
Cosí adunque visse e morí ser Cepparello da Prato e santo divenne come avete udito. Il quale negar non voglio esser possibile lui esser beato nella presenza di Dio, per ciò che, come che la sua vita fosse scellerata e malvagia, egli poté in su lo stremo aver sí fatta contrizione, che per avventura Idio ebbe misericordia di lui e nel suo regno il ricevette: ma per ciò che questo n’è occulto, secondo quello che ne può apparire ragiono, e dico costui piú tosto dovere essere nelle mani del diavolo in perdizione che in Paradiso. (Decameron 1.1.89)
So lived, so died Ser Cepperello da Prato, and came to be reputed a saint, as you have heard. Nor would I deny that it is possible that he is of the number of the blessed in the presence of God, seeing that, though his life was evil and depraved, yet he might in his last moments have made so complete an act of contrition that perchance God had mercy on him and received him into His kingdom. But, as this is hidden from us, I speak according to that which appears, and I say that he ought rather to be in the hands of the devil in hell than in Paradise. (Trans. J.M. Rigg, London, 1921, first printed 1903, taken from Decameron Web, emphasis mine)
Papal Absolution Offered in Advance
 Papal absolution was sometimes used tactically in the fraudulent way that Boniface VIII uses to seduce Guido da Montefeltro. In other words, popes sometimes took advantage of the gullibility of Christians and let their delegates suggest the promise of absolution for political advantage. The following example from a biography of Queen Elizabeth shows on the one hand sensitivity to the need to avoid a papal declaration of prior absolution and on the other the desireability of implying such a promise:
The Papal nuncio in Spain gave his opinion that the Bull of Pius V justified all her subjects in taking arms against the Queen; as regards her assassination, the Pope would not make any declaration previously, but would give the necessary absolutions after the deed had been done. (Mandell Creighton, Queen Elizabeth, p. 196, The Pergamum Collection, Kindle Edition)
The Law of Non-Contradiction and Conversion in Paradiso 6
 Dante explicitly invokes the Aristotelian law of non-contradiction in Paradiso 6, again à propos conversion, in this case that of the Emperor Justinian.
 Justinian explains that he once wrongly believed that Christ possessed only a single, divine, nature. In other words, he was a follower of the Monophysite heresy. (For the opposite heresy, the belief that Christ possessed only a single, human, nature, see the discussion of Pope Anastasius II in Inferno 10, par. 28.) Justinian explains that he was converted from that erroneous belief by Pope Agapetus I:
E prima ch’io a l’ovra fossi attento, una natura in Cristo esser, non piùe, credea, e di tal fede era contento; ma ’l benedetto Agapito, che fue sommo pastore, a la fede sincera mi dirizzò con le parole sue. (Par. 6.13-18)Before I grew attentive to this labor, I held that but one nature — and no more — was Christ's — and in that faith, I was content; but then the blessed Agapetus, he who was chief shepherd, with his words turned me to that faith which has truth and purity.
 The reference to Aristotle’s law of non-contradiction comes in Justinian’s profession of belief in Christ’s dual nature. This belief, which he originally took on faith from Agapetus, is one that he now sees as clearly as we humans see that in a set of two contradictory statements one must be true and the other false. In other words he now sees Christ’s dual nature as clearly as on earth we can grasp this elementary principle of logic:
Io li credetti; e ciò che ’n sua fede era, vegg’io or chiaro sì, come tu vedi ogni contradizione e falsa e vera. (Par. 6.19-21)I did believe him, and now clearly see his faith, as you with contradictories can see that one is true and one is false.
 The Aristotelian law of non-contradiction is cited by the devil in Inferno 27 in order to prove Guido da Montefeltro’s culpability: Guido’s non-conversion is obvious according to the most basic principles of human logic. In Paradiso 6 Justinian’s converted bliss is such that Christ’s mysterious dual nature is as obvious to him as though it were the principle of non-contradiction.