When in advance so far we had proceeded,
That it my Master pleased to show to me
The creature who once had the beauteous semblance,
He from before me moved and made me stop,
Saying: “Behold Dis, and behold the place
Where thou with fortitude must arm thyself.”

Virgil is pointing out Lucifer, also known as Dis, who has come into Dante’s view for the first time. Dis “once had the beauteous semblance” because he used to be the most beautiful of God’s angels until he rebelled against God and was banished from Heaven. Virgil’s warning that Dante must fortify himself is Dante’s warning to the reader: Prepare yourself for what you are about to read.

Oh, what a marvel it appeared to me,
When I beheld three faces on his head!
The one in front, and that vermilion was;
Two were the others, that were joined with this…
Underneath each came forth two mighty wings,
Such as befitting were so great a bird;
Sails of the sea I never saw so large.

Dante describes Lucifer’s appearance: He has three heads, each of which is a different color, and six giant wings like sails on a ship. The seraphim, the highest order of angels, are described as having six wings. But unlike an angel’s wings, Lucifer’s are featherless and leathery, like a bat’s. Dante’s description of Lucifer reflects that Dante believes that Lucifer was originally one of Heaven’s highest angels.

At every mouth he with his teeth was crunching
A sinner, in the manner of a brake,
So that he three of them tormented thus.

Dante describes how Lucifer torments the three worst sinners in Hell at once, by eating them. Dante later reveals these three sinners to be Judas Iscariot, who betrayed Jesus, and Brutus and Cassius, who betrayed Julius Caesar. All three can be seen as betrayers both of their friend and their leader. Dante’s decision to make these three men the worst of all sinners reveals his opinion of such a betrayal.

He laid fast hold upon the hairy sides;
From fell to fell descended downward then….
Exactly on the thickness of the haunch
The Guide, with labor and with hard-drawn breath,
Turned round his head where he had had his legs,
And grappled to the hair, as one who mounts,
So that to Hell I thought we were returning.
“Keep fast thy hold, for by such stairs as these…
Must we perforce depart from so much evil.”

Dante describes how he and Virgil escape from Hell by climbing down Lucifer’s body, and then climbing up the adjacent mountain that was created when Lucifer fell to earth. Although it requires great physical effort, Virgil leads Dante to the mountain, which is Purgatory. In creating this landscape, Dante reveals that he envisions Purgatory to be a place that is closer, in both location and perhaps conditions, to Hell than Heaven.