Commentary Purg XXV 128

'I know no man.'  These are part of Mary's words in answer to the angel's announcement (Luke 1:34) that she will bear a child: 'How shall this be, since I know no man?'  This is Mary's seventh appearance on the mountain as the primary exemplar of a virtue opposing the relevant vice.  Edward Moore (Moor.1899.1), pp. 63 and 194, suggests that Dante may have derived his idea of having Mary represent the 'antidote' to each of the seven sins from St. Bonaventure (Speculum Beatae Mariae Virginis).