What happens in Canto XXIV of Dante's Inferno?

Canto XXIV
Leaving the hypocrites in Pouch Six seems to have depressed Virgil. As Canto XXIV begins, Dante describes his mentor’s demeanor, comparing the great poet to a farmer in winter. This agrarian looks out over his snow-covered fields and becomes filled with worry; nothing can be accomplished while the weather is so inhospitable. However, conditions soon improve and the snow begins to melt. Relieved, the farmer then goes out to tend to his sheep.

“In that part of the youthful year wherein
The Sun his locks beneath Aquarius tempers,
And now the nights draw near to half the day,
What time the hoar-frost copies on the ground
The outward semblance of her sister white,
But little lasts the temper of her pen,
The husbandman, whose forage faileth him,
Rises, and looks, and seeth the champaign
All gleaming white, whereat he beats his flank,
Returns in doors, and up and down laments,
Like a poor wretch, who knows not what to do;
Then he returns and hope revives again,
Seeing the world has changed its countenance
In little time, and takes his shepherd's crook,
And forth the little lambs to pasture drives.”

Likewise, Virgil’s spirits improved when he and Dante finally arrive at the broken, but passable, bridge:

“Thus did the Master fill me with alarm,
When I beheld his forehead so disturbed,
And to the ailment came as soon the plaster.
For as we came unto the ruined bridge,
The Leader turned to me with that sweet look
Which at the mountain's foot I first beheld.”
Dante has his doubts about being able to safely cross the broken bridge, but Virgil urges him on but cautiously, advising:
"To that one grapple afterwards,
But try first if 'tis such that it will hold thee."

As they carefully descend, Dante thinks back to the hypocrites of the previous pouch and is grateful that his robe is not leaden; it is heavy enough as it is:

“This was no way for one clothed with a cloak;
For hardly we, he light, and I pushed upward,
Were able to ascend from jag to jag.
And had it not been, that upon that precinct
Shorter was the ascent than on the other,
He I know not, but I had been dead beat.”

Dante begins to tire from the laboriousness of the climb. He knows that were in not for Virgil’s insistence, he probably would have given up:

“Still we arrived at length upon the point
Wherefrom the last stone breaks itself asunder.
The breath was from my lungs so milked away,
When I was up, that I could go no farther,
Nay, I sat down upon my first arrival.”

Virgil is displeased. He tells his charge that laziness will not help him; indeed, laziness has never helped anyone:

"Now it behoves thee thus to put off sloth,"
My Master said; "for sitting upon down,
Or under quilt, one cometh not to fame,
Withouten which whoso his life consumes
Such vestige leaveth of himself on earth,
As smoke in air or in the water foam.”

Like a coach given a pep talk to a depleted player, Virgil tries to rally the young poet:

“And therefore raise thee up, o'ercome the anguish
With spirit that o'ercometh every battle,
If with its heavy body it sink not.
A longer stairway it behoves thee mount;
'Tis not enough from these to have departed;
Let it avail thee, if thou understand me."

It works. Dante finds a store of strength and rises, ready to move forward:

“ Then I uprose, showing myself provided
Better with breath than I did feel myself,
And said: "Go on, for I am strong and bold."

Despite his declaration, Dante is tired, in both body and soul. To keep himself going, he begins talking aloud to himself; he is surprised to soon hear another voice, faint though it is, on the other side of the bridge. The voice sounds angry. Dante tries to see into the pitch dark pouch:

“Upward we took our way along the crag,
Which jagged was, and narrow, and difficult,
And more precipitous far than that before.
Speaking I went, not to appear exhausted;
Whereat a voice from the next moat came forth,
Not well adapted to articulate words.
I know not what it said, though o'er the back
I now was of the arch that passes there;
But he seemed moved to anger who was speaking.
I was bent downward, but my living eyes
Could not attain the bottom, for the dark;”

Dante asks Virgil to help him find the voice once they cross. Virgil warns the poet to keep his exchange very short:

“Wherefore I: "Master, see that thou arrive
At the next round, and let us descend the wall;
For as from hence I hear and understand not,
So I look down and nothing I distinguish."
"Other response," he said, "I make thee not,
Except the doing; for the modest asking
Ought to be followed by the deed in silence."

There is hardly a moment to feel relief once the treacherous crossing has been traversed, for as soon as the travelers come to the other side of the bridge, they see that the ground is writhing with countless serpents. The sight is so horrific that it exceeds, in Dante’s estimation, many of the horrors he knows about. First he mentions Libya. There is a story by the Roman poet Lucan, who recounts the story of Sabellus (a collective name for Roman soliders) who is bitten by a snake; its venom liquifies the man’s body and it absorbs into the desert sands of Libya:

"Where it connects itself with the eighth bank,
And then was manifest to me the Bolgia;
And I beheld therein a terrible throng
Of serpents, and of such a monstrous kind,
That the remembrance still congeals my blood
Let Libya boast no longer with her sand;"

The names Dante mentions thereafter, Chelydri, Jaculi, Phareae, Cenchri, and Amphisbaena are all breeds of snakes that Lucan names in his work Pharsalia. The Chleydri are said to move in a cloud of smoke. The Jaculi are exceedingly fast-moving. The Pharee use their tales to make holes in ground and hide, awaiting victims. The Chenchri are said to never move in a single direction. The Amphisbaena is a terrifying, two-headed serpent. Ethopia is on the other side of Libya and it too is very hot and inhospitable:

“For if Chelydri, Jaculi, and Phareae
She breeds, with Cenchri and with Amphisbaena,
Neither so many plagues nor so malignant
E'er showed she with all Ethiopia,
Nor with whatever on the Red Sea is!”

Raising his gaze from the horrifying ground, Dante then sees naked sinners, futilely fleeing from the striking serpents. The snakes continually sink their venomous fangs into whatever flesh they are able; some bind sinners’ hands behind them while others entwine themselves around body parts they can capture:

“Among this cruel and most dismal throng
People were running naked and affrighted.
Without the hope of hole or heliotrope.
They had their hands with serpents bound behind them;
These riveted upon their reins the tail
And head, and were in front of them entwined.
And lo! at one who was upon our side
There darted forth a serpent, which transfixed him
There where the neck is knotted to the shoulders."

Once a serpent makes a clean strike, the sinner turns into a pile of ashes. Their horror is by no means over, however. Like the mythical Phoenix, each condemned soul rises again, re-formed, only to be struck and envenomed again. The tears that the sinner cries upon being rejuvenated are the spices used to embalm bodies: incense and amomum, nard, and myrrh. The “winding sheet” is what was used to wrap corpses prior to burial. The sinners’ embalmed tears are the only thing that wraps around him, instead of the traditional winding sheet:

“Nor 'O' so quickly e'er, nor 'I' was written,
As he took fire, and burned; and ashes wholly
Behoved it that in falling he became.
And when he on the ground was thus destroyed,
The ashes drew together, and of themselves
Into himself they instantly returned.
Even thus by the great sages 'tis confessed
The phoenix dies, and then is born again,
When it approaches its five-hundredth year;
On herb or grain it feeds not in its life,
But only on tears of incense and amomum,
And nard and myrrh are its last winding-sheet.
And as he is who falls, and knows not how,
By force of demons who to earth down drag him,
Or other oppilation that binds man,
When he arises and around him looks,
Wholly bewildered by the mighty anguish
Which he has suffered, and in looking sighs;
Such was that sinner after he had risen.”

Dante is properly horrified by the display. Virgil asks who the man-turned-to-ashes-and-turned-back-again is. The sinner first tells the travelers that he is a mule, one who carries out the crimes of others. Then he confesses that his true name is Vanni Fucci, previously a native of Pistoria. Dante asks Virgil to inquire of Fucci what sin had condemned him to the Seventh Pouch of the Eighth Circle. It seems that Dante had been an acquaintance of his man in Italy and that he had known him to be a man of anger; apparently Dante believes this sin should have condemned the shade to Circle Five, where the wrathful are tormented. Therefore, Dante wants Virgil to ask what greater sin the man committed:

"Tell him to stir not,
And ask what crime has thrust him here below,
For once a man of blood and wrath I saw him."

Fucci is distraught that Dante has seen him in his present condition. He finally tells the poets that his sin had been stealing holy relics from a cathedral:

"It pains me more that thou hast caught me
Amid this misery where thou seest me,
Than when I from the other life was taken.
What thou demandest I cannot deny;
So low am I put down because I robbed
The sacristy of the fair ornaments,
And falsely once 'twas laid upon another;”

After his confession, Vanni Fucci makes a prediction. He prophesies that the Pistorians will oust the Blacks, but the Blacks will fight back and be victorious over the Whites. The only reason Fucci is telling Dante, a White (“Bianco”) Guelph, this is to that it “may give thee pain."