Commentary Par XII 143-145

It has long been observed that Dante constructed these two cantos so as to make them reflect one another in a thoroughgoing way.  See the chart offered by Bosco/Reggio (who at times seem to be forcing the details to fit) for the parallel elements in Cantos XI and XII (numbers in parentheses refer to the number of terzine dedicated to each subject; square brackets contain one element not included in their table):

 Canto XICanto XII
General introduction:28-36 (3)37-45 (3)
Actions performed by the two saints:40-42 (1)34-36 (1)
Place of birth:43-51 (3)46-54 (3)
Birth:49-51 (1)55-57 (1)
[Saint's Life:55-117 (21)58-105 (16)]
Transition from biography to condemnation:118-123 (2)106-111 (2)
Condemnation of his own Order:124-129 (2)112-117 (2)
Faithful friars:130-132 (1)121-123 (1)

For a nearly identical table, without reference to any source, see Ghisalberti (Ghis.2002.1), p. 182n.