In his introduction to Dante’s Inferno, Lino Pertile, an Italian linguist and Professor of Romance Languages and Literature at Harvard University, writes:
The story that Dante recounts in the Inferno is almost entirely set in the world of the dead, yet its real target is the world of the living — the innumerable ways, all of them morally wrong, in which men and women attempt in this life to satisfy their desires for knowledge, power, and happiness. There is a progression in this negativity ranging from the love that binds Paolo and Francesca together in the infernal storm to the bestial hatred that keeps Count Ugolino gnawing at the skull of his enemy. Lucifer is the living sum of this negativity — his angelic beauty turned into extreme ugliness, his six wings incapable of lifting him one inch above the prison of ice they constantly create, his three mouths chewing forever without ever satisfying his hunger. An emblem of monstrous desire, colossal impotence, gigantic frustration.
Virgil, with Dante clinging to his neck, clambers down Lucifer’s hairy flanks and then, once they have passed the centre of all gravity, he starts climbing upward along his shanks. Lucifer, however, does not react. Unlike any of the other infernal functionaries, Lucifer seems to be completely unaware of what goes on. His six eyes weep, his tears and bloody slobber dribbling down his three chins, his six batlike wings flapping incessantly. He is a machine totally desensitized and dehumanized, that is to say, totally deprived of either emotions or intelligence. Despite what Dante says, this is not the emperor of malice, not the source of all sorrow, but rather the ultimate outcome of all evil — the supreme stupidity, futility, and hopelessness of evil — except perhaps as a ladder to goodness. This is why, once Dante is out of the “natural cavern,” we look back and ask ourselves how Hell could, indeed why it should, last forever — a point which Dante does not discuss.
The Inferno is rich in characters but, compared to the other two canticles, relatively lacking in scientific, philosophical, and theological discourse. So many are the characters who demand to be seen and heard by the unusual visitor that Dante has hardly any time for indulging in theory. However, the first canticle’s theoretical shortcomings are also its dramatic greatness, a fact that generations of readers have underlined through seven centuries by overwhelmingly favouring Inferno over both Purgatorio and Paradiso. Why do readers of all ages and of so many diverse cultures and backgrounds keep going back to the Inferno with such empathy? The reason, I submit, is not Hell’s graphic display of divine justice, but rather the tragically flawed humanity of its inhabitants. Of course, Dante condemns all mortal sinners to perpetual suffering. Yet the manner and justness of their condemnation does not engage us as much as the universal nature of their faults. Dante’s Hell is so enduring because, like the earth we know, it is so much about love gone wrong: Francesca’s love for Paolo, Farinata’s love for Florence, Piero’s love of self, Ulysses’s love of knowledge, Ugolino’s love for his children.
However, the true significance of Dante’s Hell can only be grasped within the Comedy as a whole. Divine justice shows its inflexible face in Hell, its readiness to forgive in Purgatory, and its boundless grace in Paradise. At the beginning and the end of the earthly part of Dante’s journey, Virgil and Beatrice respectively prophesy the coming of a Savior, possibly a new emperor, who will soon deliver the world from all evil. God’s Providence, which ensures the happy ending of Dante’s journey, will ultimately bring about the happy ending of the world, too. Despite the Inferno’s remorseless catalogue of human weakness and wickedness, the Comedy, as its title implies, remains a poem of hope.
— The Cambridge Companion to Dante, edited by Rachel Jacoff