Cantos 20-22

Canto 20
"Lake Benaco, fed by a thousand sources" (pg. 203). Water is usually used to symbolize purity and cleanliness, but in this case, it serves to emphasize the pain and suffering. In the first part of this Canto, the author tells about how the ground is watered by the tears of the sinners. He uses this to reinforce the contrast between good and evil. Because these people tried to contort the miracles of God into their own beliefs in magic, they are forced to be twisted in their awkward position for all eternity.
Canto 21
"The demon's pride fell so much he let loose his hook" (pg. 215). It is interesting how Dante keeps putting Virgil up on a pedestal. In this case, the demon is humbled by Virgil's words much like how most sinners can be humbled by God's words. The relationship between Dante and Virgil is similar to a religious person worshiping God. Many of the things the author says make Dante seem just as bad as the people he puts in Hell. Technically, he is worshipping someone other that the true God, so he should be punished just like the people in Hell.
Canto 22
"one must go with boozers in the tavern and saints in the church" (pg. 223). This emphasizes the fact that Dante isn't familiar with the world of Hell. He has to have Virgil as a guide because Virgil not only lives in Hell, but he has also travelled through all the levels before. It is a reminder to the reader that, since Dante isn't one of the great heroes from the past, he is very human and he needs the help. It also helps the reader to remember that Virgil is in Hell for a reason.