Commenting on a ripening stench, Virgil notes they're descending into the seventh circle. The final three rings are a class apart from the first six: here are sins of violence & treachery against others (including God), not merely sins of the mind. The book careful parses the sins in its deepest probe of metaphysics so far. It's hard to comprehend this position from our humanist point-of-view. When Dante shows pity for the hellbound, he's chastized by Virgil. The damned deserve their God-given punishments. But I can't help seeing an ambiguity in Inferno, because it describes them with such humanity.