In the second Bolgia, the Poets find the Simoniacs, or sellers of ecclesiasitic favors and offices.  This bolgia is lined with tube-like holes, in which the sinners are placed.  Their feet stick out, and are on fire.  The heat is proportinationate to their guilt.  The tubes symbolize baptismal fonts, and their stay in them is temporary.  As new sinners arrive, the old sinners are dropped through the bottoms of the holes and disappear into crevices in the rocks.

This again shows symbolic retribution.  Simoniacs mocked the holy office, and so they are turned upside down in a mockery of baptism.  They mocked the holy water of baptism, and so are baptized by fire.

In this Canto, Dante wishes to talk to one of the sinners he sees below, and so Virgil carries him down the sheer clif face until they're right beside the sinner. The sinner happens to be Pope Nicholas III, and the reason that Dante noticed him was because his feet were burning brighter than all the others, symbolizing that he is the cheif sinner in this Bolgia.

Canto XX
Home
Canto XVIII
1