Commentary Purg XII 110

The ritual occurring here, involving an adaptation of a Beatitude spoken by Jesus, will recur on the next six terraces as well.  The Sermon on the Mount seems to include eight beatitudes (Matthew 5:3-10).  For discussion of Dante's use of them, see Federigo Tollemache, 'beatitudini evangeliche,' ED.1970.1.  Tollemache points out that St. Thomas, whose discussion of the Beatitudes (ST I.ii.69.3 ad 5) seems to govern Dante's treatment of them, says there are seven, with 'Blessed are the meek' (Matthew 5:5 [5:4 in the Vulgate]) omitted, while those that 'hunger and thirst after righteousness' are remembered on separate terraces.  Thomas considers 'those who are persecuted for righteousness' sake' to refer to all of the first seven categories.  Here the reference is to the first: 'Blessed are the poor in spirit, for theirs is the kingdom of heaven.'  For a discussion of the program of the Beatitudes in Purgatorio see Chiavacci Leonardi (Chia.1984.2).