Successive sentences or verses with the same construction, so that the reader compares what changes from one to the next.
In Paradise
not to dispense two or three for six, not the fortune of the first vacant benefice, not the tithes, which belong to the poor of God
The three members have the same construction, "not to dispense", "not the fortune", "not the tithes", and the reader compares what changes: dispensation, vacant benefice, tithes. At each step the refusal becomes graver.
Cantos IX to XII: Venus and the Sun, Bonaventure, telling what Dominic asked of the apostolic see