4 ideas
Many punishments in Hell are fitted to the sin, either echoing it or inverting it: the lustful are whirled by a storm as they were by passion, and Bertran de Born carries his severed head because he divided father from son. These penalties are imposed by divine justice, and their fitting shape makes the nature of each sin visible.
In the second circle of Hell, Francesca da Rimini tells how she and her brother-in-law Paolo were reading the romance of Lancelot and Guinevere together. At the moment of the fictional kiss they kissed, 'that day we read no further,' and her husband killed them both. The pilgrim Dante, himself a writer of love poetry, is so moved by her story that he faints. The episode shows both how literature can model and license a fall and how pity can blind a judgment the poem itself upholds.
In Purgatory, Virgil explains that every human action springs from love, so every sin is love gone wrong in one of three ways. Pride, envy and wrath are love misdirected toward harming others. Sloth is love too weak toward the true good. Avarice, gluttony and lust are love excessive toward lesser goods. On this model, moral repair means reordering desire rather than suppressing it.
Hell is ranked by kind of sin: incontinence (failure of self-control) sits highest and lightest, violence below it, and fraud and treachery deepest, inside the walled City of Dis. Fraud ranks worst because it corrupts reason, the faculty unique to humans, and it destroys the trust that makes community possible. Betrayers of kin, country, guests and lords lie frozen at the bottom, the coldest point, farthest from love.