A stammering woman came to me in dream:The siren may seem to represent sexual temptation, perhaps as a synecdoche for the whole class of sins of excessive love. However, Dante's characteristic sin is pride, and his error in the dream is one of pride, not desire at all: he fondly imagines that his gaze corrects the defects of her body. His imaginative eye has the power to "loosen her tongue… set her contorted limbs in perfect order… and [transform] the wanness of her features." Like all great poets, Dante seems to himself to be the source of redemption, his inspiration a saving vision of a deformed world.
her eyes askew, and crooked on her feet,
her hands were crippled, her complexion sallow.
I looked at her; and just as sun revives
cold limbs that night made numb, so did my gaze
loosen her tongue and then, in little time,
set her contorted limbs in perfect order;
and, with the coloring that love prefers,
my eyes transformed the wanness of her features.
And when her speech had been set free, then she
began to sing so, that it would have been
most difficult for me to turn aside.
"I am," she sang, "I am the pleasing siren,
who in midsea leads mariners astray—
there is so much delight in hearing me.
I turned aside Ulysses, although he
had longed to journey; who grows used to me
seldom departs--I satisfy him so."
Her lips were not yet done when, there beside me,
a woman showed herself, alert and saintly,
to cast the siren into much confusion.
"O Virgil, Virgil, tell me: who is this?"
she asked most scornfully; and he came forward,
his eyes intent upon that honest one.
He seized the other, baring her in front,
tearing her clothes, and showing me her belly;
the stench that came from there awakened me.
--Purgatorio, IX.7-33 (tr. Allen Mandelbaum)
Disabused of this unspoken self-interpretation, he is stricken to the heart; he now trudges on "bearing my brow like one whose thoughts have weighed him down, who bends as if he were the semiarch that forms a bridge." A bridge may seem rather a grand structure, but is invoked here to describe the posture of shame. A semiarch aims upward, but trains its ambition to reach across, making itself serviceable rather than aspiring higher. This self-humbling form is essential to its function, and in the same way Dante's castigations of his own pride are essential to the poem.
Herein lies the central thematic paradox of the whole Divine Comedy: Dante must learn and practice humility, even as he takes on a grand mission that places him analogically in the position of creator, judge, and redeemer. Only by living this paradox can Dante appreciate the mystery of his final vision, the incommensurable achievement of the Incarnation:
so I searched that strange sight: I wished to see
the way in which our human effigy
suited the circle and found place in it—