A vertical reading of Dante's Purgatorio 4

One way of reading Dante's Divine Comedy is 'vertically', which means analyzing same-numbered cantos from two or three parts of the poem (canticles), Inferno, Purgatorio, Paradiso, for symmetrical meanings which become enriched by this clever juxtaposition. This is based on the presupposition that Dante built this symmetry into the poem as a whole, and …