Dante takes the opportunity to remind us again that it is dawn, with a pretty personification of Aurora’s (goddess of the dawn) cheeks changing color—from pale white to orange—as she ages.
Dante spies something in the water. It’s glowing like the planet Mars in the morning as it approaches. Dante also compares it to a flying bird.
Dante turns to Virgil to ask the inevitable question: what the heck is that?
Virgil isn't not curious—he knows exactly what's happening. He orders Dante to kneel and join his hands in prayer. This shiny white guy must be important.
The glowing figure just happens to be an angel of God—as Virgil tells us.
Virgil raves adoringly: “Look—our pretty angel is simply too good for mortal means. He will only use his wings as sails and oars. And look how they point to heaven, and always stay milky-white, because they’re immortal!”
As the angel gets closer, Dante has to turn his eyes away to keep from being blinded.
The angel reaches the shore, guiding a boat.
Because he can’t look at the angel, Dante has to content himself with looking at the boat. He notes that there are at least a hundred souls seated within.
The souls are all singing a psalm. The Latin words, “In exitu Israel de Aegypto,” come from Psalm 114 and translate as “During the departure of Israel from Egypt.”
The angel makes the sign of the cross over the souls, who fling themselves to the ground. The boat leaves.
The new arrivals gape as they look around and, finally seeing Dante, they ask him how they can climb the mountain. (If you haven’t figured it out yet, the souls are penitents sent to Purgatory to cleanse themselves of sin.)
Because Dante is just as gape-mouthed as the penitents, Virgil answers to this effect: we may look like we’re experts, but we’re just as lost as you. We came from Hell. Lucky us, right?
The penitents aren't listening. They’ve all fixated on Dante, who is (gasp) still living, and they turn pale in astonishment.
Now the center of attention, the ever-so-humble Dante compares himself to a messenger of peace (complete with the olive branch), around whom everyone crowds to hear the good news.
One soul admires Dante so much that he actually steps forward to hug the poet. Dante returns the gesture—not because he’s reveling in his celebrity, but because he recognizes the admirer.
We have a problem here: Dante can’t hug him because the souls are only shades. They don't have bodies. So Dante’s hands go straight through him. Three times. Because it takes him three tries to realize what's going on.
The soul comforts him, reassures him that he loves Dante, and then asks him why he’s here.
Dante gives him the short version, identifies the soul as Casella, and then asks him why it’s taken him so long to arrive here. This implies that Casella died a while ago—certainly before Dante’s journey through Hell.
Casella doesn’t give a straight answer. He says the Helmsman Angel (the one guiding the boat of penitents souls) can pick and choose whom he wants to take first, even though he’s been taking all comers for the past three months.
But there’s no harm done, insists Casella, since the angel’s will is God’s will. So Casella waited at Ostia, Rome’s port at the mouth of the river Tiber, to cross. In case you didn’t know, Ostia is where all souls who aren’t damned to Hell gather to cross to Purgatory.
Then Dante asks for Casella to sing and Casella complies. (Apparently, these two were musical partners in the good ol’ days; Dante wrote the poetry, Casella set it to song.) He sings a love song.
Casella’s voice is so beautiful that his singing hypnotizes everyone, including Virgil. They all gather motionlessly around Casella.
Then Cato breaks up the fun. He shouts at them to stop dilly-dallying with their silly music and get on with the business of purgation.
Metaphor time! Casella’s audience breaks up like a flock of feeding doves interrupted by some scary beast. They all rush towards the slope of the mountain.
Our heroes, Dante and Virgil, follow just as quickly.