The third terrace is thick with acrid, black smoke — the wrathful move through a blindness of their own making, a literalization of rage's effect on vision. Dante cannot see his hand before his face. He clings to Virgil as they hear souls singing the Agnus Dei — "Lamb of God, who takes away the sins of the world, grant them peace." The hymn in the darkness is deeply affecting: these are not the howling damned; they are penitents asking for peace from the very rage that once consumed them.
Marco Lombardo emerges from the smoke. He is a famous Lombard courtier of the 13th century, celebrated for his courtesy and wisdom. He engages Dante in one of the most philosophically substantial conversations in the whole poem. Dante puts to him the question: why is the world so corrupt? Is it the stars? Is it fate? Marco answers with controlled force: the fault is not in our stars but in ourselves. God gave humanity free will, and the soul comes into the world knowing only its first joys; it pursues pleasure without direction, like a child, unless guided. For this guiding, God gave two lights: the Pope (to lead souls to God) and the Emperor (to guide civil life). Now — and here is Marco's great diagnostic — these two lights have been merged into one. The Church has seized temporal power, conflating the two roles. With no independent emperor to check it, the Church has grown corrupt; with no Church holding the emperor to spiritual account, civil life has degraded. Italy suffers from a theological administrative error. Dante agrees passionately: this separation of powers is not merely political theory but cosmological necessity.