I did not open them—for to be rude
To such a one as him was courtesy.

Dante speaks these lines in reference to a promise, in Canto XXXIII, to open Fra Alberigo’s eyes for him (XXXIII.146–147). Alberigo, one of the living men who was snatched and brought to Hell before they died because of the magnitude of their sins, is lying supine in Cocytus, the frozen lake; his tears have frozen over his eyes, and he has asked Dante to remove the rings of ice from his eyes so that he might cry freely for a time. Dante initially agrees, but after he realizes the extent of the man’s evil, he changes his mind and recants his promise, taking pleasure in Alberigo’s suffering.

This quote is extremely important to Dante’s overall development in the poem, indicating the extent to which he learns not to pity suffering sinners and to despise sin wholeheartedly. At the beginning of Inferno, Dante weeps for many of the suffering souls; by the penultimate canto, he doesn’t even help them weep for themselves. This attitude, wholly endorsed by Virgil, may seem harsh to the modern reader, but it is portrayed in Inferno as Dante’s necessary first step toward overcoming sin in his own life and finding salvation in God.